Before we get started, a small disclaimer: we used the HTC One for nine days, five of which were on a pre-production unit that was shipped to us last week. We wanted to spend as much time with this device as possible because it's a major endeavor for HTC and is one that the CEO is even reportedly betting his job on. Our device was unlocked and used on AT&T's HSPA+ network, so we won't discuss how it will work on U.S. carriers with LTE networks.

We're not going to beat around the bush, the HTC One is HTC's best smartphone yet . Hold on to your hat and don't jump to the end of this review right away, we have a lot to discuss because it offers tons of new software services aside from an amazing industrial design that looks like the brainchild of Apple's Jonny Ive.

Hardware

HTC knew that Samsung was going to release the Galaxy S4 sometime soon. It also knows Apple's iPhone 5S is on the horizon, likely due out this summer. It knew it needed to create something stunning, something that took the breath away from any consumer that held its smartphone. It achieved that goal. The HTC One is the finest device we've ever seen from the Taiwan-based company, and it's largely due to an incredible focus on design and the build quality down to every aspect of the phone. The device is crafted out a single block of aluminum, which means you have a uni-body design that feels solid as a brick. That means small joys, like enjoying the cool touch of metal when you pick up the phone to turn your alarm off in the morning.

To put it simply, the screen is to die for. It packs a full 1080p resolution into a 4.7-inch display, which means you're getting an even sharper pixel density (469ppi) than the DROID DNA/HTC Butterfly, since those have larger 5-inch screens and the pixels spread out more. The quality of the display looks almost fake, and we found that it really pushes the boundaries of what we expect from a smartphone. Simply saying that it's incredible doesn't do it justice, though, it's the best screen on a phone we've ever seen. You need to go see it for yourself to see just how amazing text, videos and photos look on the One.

Now to cover the basics: moving around the phone you'll find that it's very minimal. There's the aforementioned 4-ultrapixel camera and LED flash on the back, a small white plastic border running all around the phone for the antennas, brushed metal volume buttons on the right-hand side, a front-facing wide-angle camera for video chat and self-portraits, stereo "Boom Sound" speakers on the front face, a microUSB port on the bottom, and a power button on the top-left that doubles as an IR blaster for controlling your TV. We'll discuss that in detail later.

We can talk about the hardware forever, but we really urge you to go see the phone for yourself to see just how amazing it is.

.. you're getting an even sharper pixel density (469ppi) than the DROID DNA/HTC Butterfly..

Software

HTC added its latest custom skin to the HTC One and it's aptly named Sense 5 as the fifth iteration of the software. Sense 5 is more about the entire user experience than just the software, however, and that means the hardware/software behind Boom Sound, the Zoe camera and more. We'll discuss those, but really what you need to know is that it's the best version of Sense yet. The home screen is automatically set to a new feature called "BlinkFeed" that pulls in news stories and images based on your tastes. If you dig sports, you can filter it to all sports. If you love politics and mobile, you can have those stories populate as well. It also has an option to add in Twitter and Facebook feeds. I generally love BlinkFeed, but I've talked to other reviewers that weren't fond of the experience and preferred a regular home screen. That's an option you can set, but BlinkFeed never disappears and is instead relegated to another area of your home panels.

I generally use Gmail for all of my email purposes, but Jonathan Rettinger loved HTC's email client on the One and found that it was clean and responsive to use. We also enjoyed that you can easily organize applications by choosing between different grid sizes. If you want, you can display apps alphabetically, by the most recent used, or in a custom fashion you choose. HTC also lets you choose between 3 x 4 and 4 x 5 grid sizes, which helps alleviate a cluttered feeling.

We should also note that HTC's set up application is truly amazing. You can easily use it to transfer your contacts, text messages, settings, media and applications from another Android phone (it's dead simple to use, just follow the steps and you're golden) or even from a BlackBerry or iPhone. You can also choose to back your data up to the cloud so that you can restore your phone again should you lose it or replace it with a new HTC device.

HTC's multitasking window can be accessed by tapping the Home button twice. It's fantastic and lets you easily swipe away any open applications. That said, the button layout is a little annoying and we wish there was an easier way to access multitasking without double tapping (like holding the back key, maybe). We're fans of the touch keys – some prefer a software method – but HTC said that it didn't want to waste screen real estate and we think that makes a lot of sense.

The new lock screen is awesome and clean. It shows a preview of any new text messages and also sports HTC's brand new and clean weather widget, as well as the date and time. You can customize the home screen apps to those of your liking, but it defaults to text messages, the browser, your phone and the camera. Simply drag and of them to the center of the screen and the app launches.

Take this away: Sense 5 is awesome and is generally a joy to use. We'll discuss some of the other features later in this review where appropriate.

Sense 5 is awesome and is generally a joy to use.

TV Controls

HTC added its own application called "TV" that takes advantage of the IR blaster built into the home button. It's easy to setup, just turn off your TV and follow the instructions as it programs itself with your cable box and television.

The application is basically a re-skinned version of Peel, a popular Android application, and provides recommendations, shows you what's on TV and generally just lets you do what your TV remote lets you do. There are limitations, however. You can't set your TiVo, and you can't access Netflix or other third-party applications. Those seem like natural progressions for the software in the future, but they aren't there now.

We love that you can set it to alert you of your favorite shows, however, and that it remains in your notification bar while the TV is on. It even shows the last few shows you watched so you can quickly swap between channels.

We took the One to a restaurant nearby and secretly set up the TV application with a TV that happened to be off. After checking the brand and following the steps, we were soon in complete control of the TV. It was certainly fun changing the New York Ranger's game to SpongeBob Squarepants.

Camera

HTC took a big bet by outfitting the One with a four "ultrapixel" camera instead of participating in the megapixel race. If you're unaware, most phone makers are trying to offer 13-megapixel cameras right now, but HTC doesn't see the value in that. Instead, it wanted to focus on quality and so added a sensor that takes in more light for higher quality pictures in both light and dim shots, without too much noise and with as much accuracy as possible.

We found that the low light shots were amazing, largely due to the increased sensor size, and that the camera is one of the best on the market right now right up there with Nokia's Lumia 920. HTC, indeed, was able to prove that it's not all about megapixels. Our only gripe is that digitally zoomed images started to show the lack of megapixels, otherwise both video and photos looked stellar. We noticed popping noise on our video with the pre-production unit, but that was gone on the final hardware.

We found that the low light shots were amazing … the camera is one of the best on the market right now.

Now on to the fun stuff. HTC added what it calls "Zoe" shots to the camera's functionality. It allows you to record quick 3 second clips of video as you snap photos. Your pictures and Zoes are all stored in an "events" folder, and tapping the top photo in this album combines a total of 13 Zoes and photos to make a highlight reel. You can select which ones to include, but it's a bit of an effort if you want to separate events into specific categories.

For example, I shot a few Zoes and photos of my friend's new puppy before celebrating St. Patrick' day. At the end of the day, however, the entire events folder included all of these photos and Zoes. I had to manually move all of the puppy photos to a separate event to create my own highlight reel.

Highlight reels are amazing however, and it's something I truly love about the HTC One. The 30 second clip switches between panning around photos and suddenly shows a small video, as if bringing the whole day to life. HTC includes its own tunes to each highlight reel, which match up with one of a half-dozen pre-set filters.

Boom Sound

HTC Boom Sound, which we mentioned earlier, not only involves the stereo speakers on the front of the device but the entire audio experience. That includes Beats Audio, which was stellar as usual, but a little heavy on the bass, dual-microphones for clear call quality at all times and more. In fact, those dual-microphones help record audio in a live environment, so if you're at a concert you can record the audio and play it back without the muffled insanity that usually comes through from a loud recording.

The front-facing speakers sound incredible, however, and really provide an immersive experience both while listening to music or watching videos. They were loud enough to play back a YouTube clip in a crowded restaurant, even.

Call Quality

As usual, call quality was stellar. We tested the phone on AT&T's network in New York and in California and had no complaints whatsoever. The dual-mics helped keep out background noise and the stereo speakers made conference calls crystal clear with the speakerphone activated.

Performance

HTC's One scored 11,850 on Quadrant, but it's not always about numbers. We found the day-to-day performance to be buttery smooth, likely a nod to the Qualcomm Snapdragon 600 processor and the 2GB of RAM. We never experienced lag while navigating around Sense 5, applications opened and closed quickly, and we were able to run multiple applications at once with nary a stutter in performance. You expect speed from a flagship phone and the One doesn't disappoint.

Battery Life

The HTC One fared pretty well with battery life, but you need to remember this unit didn't support 4G LTE networks in the U.S., which is a big drain. The device sports a 2,300mAh battery, and we were able to take the device off the charger at 7:00 a.m and use it for 2-3 hours of talk time, leave two separate email accounts checking email every 5 minutes throughout the day and leave BlinkFeed, Twitter, Facebook running. We also had the brightness set to around 80 percent and used the phone to surf the Internet throughout the day. By midnight we put it back on the charger with about 35 percent of the battery left. That's on a par with most other devices, but again, we'll reserve our full battery life rating for when we see how it handles LTE networks.

Some Gripes

We have a few gripes with the One, but they were far from deal-breakers. First, the GPS had a hard time updating quickly as we moved to different places and turned it on. Second, we sort of wish HTC offered expandable storage so that we could boost the 32GB of onboard storage (or 64GB, but our unit had 32GB), however, that's simply a restriction with the aluminum unibody design of the phone. Plus, as we move to cloud storage and streaming services, it's not as important as it used to be. We also forgive the non-removable battery design, but we know that's going to be a worry for a lot of consumers.

Wrap-Up

We're still in love with it and carrying it day-to-day, because it offers so many features that can't be found in any other product on the market right now. From the stellar camera and its highlight reels to the aluminum body and stellar screen, the HTC One offers a truly first-class experience. HTC didn't only hit this thing out of the park, it hit it into orbit, where it will aggressively compete with Samsung's Galaxy S4. It's so close to perfect we're awarding it a well-deserved 9.5 / 10 and an editor's choice.

We recently tested the HTC One for AT&T. We found that battery life dropped 3-5 percent due to the added LTE support, which is admirable and still excellent. That's also while using the phone under the same usage scenarios as before.

We also like that AT&T's branding isn't invasive at all, instead there's just a small logo on the back of the HTC One.

Update: One big gripe we have, however, is that T-Mobile and Sprint will support HTC's amazing backup solution that makes it easy to move from another device, including the iPhone, to the HTC One. AT&T's model, however, relies on AT&T's own device backup software that isn't as good.

In general, the device is just as awesome as the international version we tested but with added AT&T 4G LTE support. It is very much is one of the best smartphones available in the world right now.

Editor's Note: Jonathan Rettinger and Todd Haselton wrote this review together.