The world’s most popular smartphone becomes significantly faster, thinner and lighter this week, while gaining a larger, 4-inch screen — all without giving up battery life, comfort in the hand and high-quality construction.

That’s my quick take on Apple’s new iPhone 5, the sixth generation of the iconic device, which goes on sale on Friday. I’ve been testing the new iPhone for nearly a week and I like it a lot and can recommend it, despite a few negatives, such as a new maps app that has one big plus, but other big minuses. On balance, I still consider the iPhone the best smartphone on the market, especially with its staggering 700,000 third-party apps and a wealth of available content.

The price is the same — $199 for a 16-gigabyte base model, with higher-memory models at $299 and $399, all requiring a two-year contract.

Bigger Screen

In increasing the iPhone’s screen size, Apple took a different approach than competitors. It kept the same side-to-side width, yet added height to grow the screen from its previous 3.5-inch size. For those who prefer the gargantuan screens on some other phones, like the 4.8-inch display on Samsung’s Galaxy S III, the iPhone 5’s screen likely won’t suffice. These competing big screens are typically both taller and wider.





iPhone 5 iPhone 5

However, I found the new iPhone screen much easier to hold and manipulate than its larger rivals and preferred it. In my view, Apple’s approach makes the phone far more comfortable to use, especially one-handed. It’s easier to carry in a pocket or purse and more natural-looking when held up to your face for a call.

And the moment you turn it on, you notice that the new, larger, screen can display more content—six rows of icons instead of five; and more contacts, emails and calendar entries without scrolling.

Despite the larger size, Apple managed to retain the same number of pixels per inch on the iPhone 5 as on earlier models, so the new model keeps the “Retina display” effect, which allows for sharp details. The screen continues to look great.

There’s a temporary downside: Many apps will fail to fill the whole of the larger screen until they are revised. But they still work as intended.

Design

While this new model isn’t a radical redesign, it offers a much bigger change than the current iPhone 4S did when it was launched last year. The minute you pick the iPhone 5 up you notice it’s much lighter—20 percent lighter, in fact. It’s so much lighter that you wonder if it’s a demonstration mock-up, not the real thing.

Yet unlike many competitors, this isn’t a plastic, insubstantial-feeling device. Although Apple claims it’s the world’s thinnest smartphone—18 percent thinner than the prior model—the iPhone 5 retains Apple’s trademark, solid-feeling, metal construction, with an aluminum back this time, instead of a glass back. Like many Apple products, it’s gorgeous.

There’s one design change that’s already rankling people, however: To accommodate the thinner design, Apple has adopted a new, thinner connector on the phone for plugging in the charger cable and connecting to accessories, like speaker docks. A new cable is included, but owners of the new phone will have to buy $29 adapters to keep using existing accessories.

The iPhone 5 also boasts a large array of new software features — though nearly all are available for older iPhones as well, via a free upgrade to the operating system, called iOS 6.

Speed, Battery and Camera

Perhaps the single biggest functional improvement in this iPhone — something you can’t get by upgrading the software on an older model — is speed. Apple has finally connected the iPhone to the fastest cellular data network, called LTE, and data downloads and uploads just fly, even when you aren’t on Wi-Fi. Also, the processor now has twice the previous speed.

Apple is hardly the first smartphone maker to include LTE. In fact, it’s one of the last. But including it in the popular iPhone is a big deal, especially since, unlike on some early LTE models, the blazing cellular technology doesn’t decimate the battery life on this phone.

Using an iPhone 5 on the Verizon LTE network in Silicon Valley and Washington, D.C., I averaged almost 26 megabits per second for downloads and almost 13 megabits per second for uploads. Download speeds peaked at 42 megabits per second. These speeds are more than 10 times the typical speeds I got on an iPhone 4S running Verizon’s slower 3G network and are faster than most Americans’ home Internet services. While LTE affects only data, voice calls I made on the iPhone 5 were clear, better than in the past. I had no dropped calls.

The iPhone 5’s battery lasted between 9 and 12 hours every day, in mixed use. For most people, the phone would last the day without recharging.

Apple shrunk the size of the rear camera, but kept the 8-megapixel resolution and added a cool, easy panorama feature and the ability to take still photos while making a video. Photos and videos I took looked great and were improved when in low light.

Maps and Software

Google vs. Apple Compare screen shots of Google’s maps app and Apple’s own maps app.

iPhone 5 White House map (Apple Maps) iPhone 5 White House map (Apple Maps)

iPhone 4S White House map (Google Maps) iPhone 4S White House map (Google Maps)

iPhone 5 navigation (Apple Maps) iPhone 5 navigation (Apple Maps)

iPhone 4S navigation (Google Maps) iPhone 4S navigation (Google Maps)

The biggest drawback I found is the new Maps app. Apple has replaced Google Maps with a new maps app of its own. This app has one huge advantage over the iPhone version of Google Maps — it now offers free, voice-prompted, turn-by-turn navigation. Google had made this available on its Android phones, but not the iPhone. Apple’s navigation worked very well, with clear directions displayed as large green highway signs.

But the app is in other ways a step backward from the familiar Google app. For instance, while Apple’s maps feature a 3-D “Flyover” view of some central cities, they lack Google’s very useful ground-level photographic street views. And they also lack public-transit routing. Apple will instead link you to third-party transit apps. Also, while I found Apple’s maps accurate, they tend to default to a more zoomed-in view than Google’s, making them look emptier until you zoom out.

Siri, Apple’s voice-controlled intelligent assistant, can still be unreliable (it’s still a beta) but I had success with some of its new features, such as looking up movies and sports scores. It now allows you to dictate and post Facebook status messages and book restaurant reservations via the separate OpenTable app.

Speaking of Facebook, Apple has added sharing to that service as a built-in feature that works with many apps on the phone.

There’s also a nice new feature that lets you respond to a call you can’t take with either a canned text message (such as “I’ll call you later”) or a reminder to call back.

Apple’s FaceTime video-calling service now works over cellular connections as well as Wi-Fi. I was able to make several crystal-clear video calls over LTE, one from a parked car.

And Apple is introducing a new photo-sharing service, which lets you set up a stream of selected pictures and invite specific friends to subscribe to it. Any new pictures you add to these shared Photo Streams pop up on subscribers’ phones and they can comment on them.





Siri on the iPhone 5 can look up movies and sports information, above, as well as make restaurant reservations via the separate OpenTable app. Siri on the iPhone 5 can look up movies and sports information, above, as well as make restaurant reservations via the separate OpenTable app.

Some rival phones boast some features Apple chose to omit. These include a wireless function called NFC, for paying for goods wirelessly, and face recognition for logging into your phone. But I regard such features as either little-used or unperfected. For instance, NFC isn’t available in most stores and, in my tests, facial recognition on phones has failed to work time and again. For some, these features matter a lot, but I’d bet most users won’t care about them, at least in their current state.

Carrier Plans

Carrier plans for the new iPhone are too complex to detail here. In general, if you’re a current iPhone user, you won’t be able to upgrade at the $199 price unless you’ve had your current phone for a minimum period. And unlimited-data plans generally aren’t available to new users, though Verizon will sell you one if you are an existing customer with unlimited data and pay an unsubsidized price of $649 for the phone. AT&T will allow existing users with unlimited plans to keep them, even at the subsidized phone price, if they’ve had their current iPhones for a certain length of time, generally around 20 months. Sprint is the exception: It offers unlimited data to all iPhone buyers, existing and new.

Upgrading

If you own an iPhone 4S and especially if your carrier won’t let you upgrade yet at the $199 price, you may be content with just upgrading to the new software, which gives you a lot. But you’ll be stuck with the smaller screen, bulkier size and pokier cellular speed. If you own an older model iPhone, or are switching from another phone, however, the iPhone 5 is an excellent choice.

Bottom Line

Apple has taken an already great product and made it better, overall. Consumers who prefer huge screens or certain marginal features have plenty of other choices, but the iPhone 5 is an excellent choice.

Email Walt at mossberg@wsj.com.