The OnePlus 3 is the latest top-end smartphone sold at mid-range prices from Chinese manufacturer OnePlus, which offers a refined experience for considerably less than Samsung, HTC, LG or Apple.

The 3 is the fourth smartphone from OnePlus – a small Chinese startup aiming to provide the best experience possible product for significantly less money than rivals – and is a big step in all directions over last year’s OnePlus 2.

Aluminium top to bottom

The capacitive buttons either side of the home button can be swapped sides, should you want the back button on the right. Photograph: Samuel Gibbs/The Guardian

The OnePlus 3 is an all-metal phone with a slightly curved back, smooth edges and contoured glass front that tapers off towards the edges. It feels very well put together, really great in the hand and as good as the very best from high-priced rivals.

The 5.5in full HD screen is vibrant, with inky blacks, rich colours and excellently white whites. It isn’t as high resolution, and therefore not as pixel-dense as the Samsung Galaxy S7 Edge, however, which is noticeable side-by-side. It’s also not great for use in virtual-reality headsets, but most buyers will be happy with the quality of the screen.

The display also has very narrow bezels either side, which makes the OnePlus 3 quite narrow for a large-screened smartphone, and more manageable than most because the overall size of the device is kept quite small. Compared to the best 5.5in smartphone available, the Samsung Galaxy S7 Edge with its curved screen, the OnePlus 3 is only 2.1mm wider. It’s also only 1.8mm taller than the Samsung.

The notification slider is great. Google should make it a standard part of an Android phone. Photograph: Samuel Gibbs/The Guardian

One of the things unique to OnePlus is a notification slider on the side of the phone that switches between silent, priority and all notifications. It’s great and every Android phone should have one.

Specifications

Screen: 5.5in full HD AMOLED (401ppi)

5.5in full HD AMOLED (401ppi) Processor: quad-core Qualcomm Snapdragon 820

quad-core Qualcomm Snapdragon 820 RAM: 6GB of RAM

6GB of RAM Storage: 64GB

64GB Operating system: Android 6.0.1 OxygenOS

Android 6.0.1 OxygenOS Camera: 16MP rear camera with OIS, 8MP front-facing camera

16MP rear camera with OIS, 8MP front-facing camera Connectivity: LTE, Dual-Sim, Wi-Fi, NFC, USB-C, Bluetooth 4.2 and GPS

LTE, Dual-Sim, Wi-Fi, NFC, USB-C, Bluetooth 4.2 and GPS Dimensions: 152.7 x 74.7 x 7.35 mm

152.7 x 74.7 x 7.35 mm Weight: 158g

Top spec is almost overkill

Dual Sim support is unusual in the UK, particularly for a top-spec smartphone. Photograph: Samuel Gibbs/The Guardian

The OnePlus 3 runs Qualcomm’s latest top-end smartphone chip, the Snapdragon 820, which will likely power most of the flagship smartphones for the remainder of 2016. It’s a pretty powerful chip that will handle almost anything anyone is likely to try to do with a smartphone.

One thing that sets the OnePlus 3 apart from the pack is its 6GB of RAM. Most smartphones have 2 or 3GB, with some such as the Galaxy S7 Edge having 4GB. The more RAM a phone has the more apps and tabs in the browser they can have open at the same time, but frankly 6GB is a bit overkill for what’s possible at the moment. Looking at the memory monitor built into Android, of the 5.6GB of RAM available, I barely ever used more than 3.5GB. As with computers, however, you’re only ever going to need more memory as things progress, so you could look at it as future-proofing.

The OnePlus 3 was snappy and performed well throughout my testing, with little in the way of noticeable lag or stutter anywhere. It even handled 30-minute gaming sessions without getting too hot on a day when ambient temperature hit 25C.

Used as my primary device with four hours of listening to music through Bluetooth headphones, three hours spent browsing or using apps, occasional gaming and taking photos, with hundreds of push notifications throughout the day, the OnePlus 3 lasted just over 24 hours between charges.

I noticed that battery life during the day was quite good - on par with some of the more power efficient smartphones - but that standby time overnight was poor, losing between 12 and 16% of charge while left on silent on a bedside table for seven hours. Most devices lose around 1% of charge per hour.

Dash Charge

Dash Charge looks and operates just like any other fast charging solution, but the phone doesn’t get hot and you can use it while it charges and still top it up at the maximum rate. Photograph: Samuel Gibbs/The Guardian

OnePlus has licensed sister Chinese smartphone manufacture Oppo’s fast charging technology, which operates differently than most other quick charging solutions by moving the fast charging chips to the power adapter, rather than the phone. The Dash Charge system moves the largest source of heat during charging from the cramped confines of the phone near the battery to something plugged into the wall, meaning the phone can charge faster without you having to worry about it overheating.

Charging from zero to 100% took 72 minutes, while zero to 75% took 36 minutes. That’s not a lot faster than the best of the rest when not in use. The difference is that the phone didn’t heat up at all, and could be used like normal without impacting the charging rate. Most devices get too hot and must slow down the charging speed, particularly when someone is using the device with the screen on.

The downside is that if you charge the OnePlus 3 via any non Dash-charge compatible power adapters, such as a computer, the phone charges at the slow, normal rate. Dash chargers cost £16 each - so it’s worth buying another with the phone.

The OnePlus 3 is also a dual-Sim phone, which is quite rare in the UK, meaning you can have two different plans, networks and phone numbers connecting to one phone - useful for carrying a work phone and personal phone in one device, for instance.

Better still, it can support two Sim cards in standby simultaneously, which means both cards can be connected to a 4G/3G network at the same time. Most only support one card in 2G mode, discounting networks such as the UK’s Three, which do not use a 2G signal.

OxygenOS, unless you don’t like it

OxygenOS is good, but an open bootloader means you can change it for another version of Android if you want. Photograph: Samuel Gibbs/The Guardian

OnePlus produces a custom version of Android called OxygenOS. The latest version is based on Android 6.0.1 Marshmallow and on the face of it looks no different from the version of Android running on Google’s Nexus smartphones.

OxygenOS has a slightly different launcher with the company’s so-called Shelf on the left-most homescreen pane - a place for putting widgets, apps icons and the weather. Users can also have on-screen navigation buttons, or using the capacitive touch ones below the screen to save space as well as customise what they do.

The Shelf is about the only difference between Google’s Nexus Android version. Photograph: Samuel Gibbs/The Guardian

For instance, I set a double tap of the recently used apps button to immediate switch to the last used app - a feature that’s been added to the next version of Android N. A selection of other gestures, as well as an ambient display mode that wakes the screen when notifications come in or uses the camera to detect when your hand is over the screen to wake up, are also available.

OxygenOS is one of the better, stripped back and bloat-free versions of Android.

Fingerprint scanner

The OnePlus 3 fingerprint scanner is one of the best home-button style sensors available. Photograph: Samuel Gibbs/The Guardian

The home button functions as a fingerprint scanner, which is fast and responsive. Most of the time it would recognise my thumb first time, but occasionally would struggle when my thumb didn’t quite cover the whole sensor at odd angles.

It is significantly improved over the OnePlus 2, and only slightly worse than the very best from Huawei.

Camera

The OnePlus camera app tries to make it hard to take a bad photo and succeeds for the most part. Photograph: Samuel Gibbs/The Guardian

The main 16-megapixel camera on the back is capable of some pretty good shots across varied lighting conditions. With good lighting the camera produces detailed pictures with fairly lifelike colours without much trouble. In difficult lighting conditions, such as those under artificial light, the images can look a bit grainy at full crop.

It’s not quite the best camera available, but it’s still up there with smartphones costing half as much again.

The camera app is relatively simple to use to get good pictures, and has full manual controls with RAW support if so desired. Slow motion 720p video at 120fps is also available, with 4K recording at 30fps if required.

The 8-megapixel selfie camera on the front produces some of the most detailed selfies I’ve seen, even in relatively difficult lightning conditions.

Observations

The grey aluminium has a slight red tint to it in certain lights

The tiny bezels made it easier to hold, but I found it quite easy to activate the capacitive navigation buttons with my palm

Silencing the phone with the notification slider is easy and fast

Dash Chargers power other devices up to 2A, which is normal charging rate

OnePlus sells a Dash car charger for £25

It’s got NFC, which the OnePlus 2 oddly didn’t - good for Android Pay

The phone ships with an unlocked bootloader making it easier to load custom Android versions, should you not like OxygenOS

It comes with a screen protector pre-installed, but like most screen protectors on contoured or curved glass, stands out like a sore thumb.

The curved aluminium back feels great in the hand and belays its £309 price. Photograph: Samuel Gibbs/The Guardian

Price

The OnePlus 3 costs £309 ($399) available in grey with a gold colour available later. The phone will be available straight from OnePlus without the company’s controversial invite system.

For comparison, the 5.5in Samsung Galaxy S7 Edge costs £639, the Google Nexus 6P costs £449 and the Huawei P9 Plus costs £500.

Verdict

Previous OnePlus smartphones have claimed to be “flagship killers”. That’s still not quite accurate, but the OnePlus 3 is a very good smartphone priced at less than half the price of top rivals.

For your £309 you get a beautiful, well-made metal smartphone, with reasonable battery life, good screen and cameras, and snappy performance. You also get dual-Sim support and 64GB of storage built in. It is easily the best smartphone OnePlus has made.

The biggest complaint of previous OnePlus smartphones was how difficult they were to actually buy, which shouldn’t be the case any more, while the company has worked hard to improve support options.

There’s still a question over the speed of software updates, but for a top-spec smartphone at a mid-range price, you don’t get much better than the OnePlus 3.

Pros: all-metal, great fingerprint sensor, good screen, fast charging, good cameras, excellent notification slider, dual-Sim with dual standby, cheaper than rivals Cons: no removable battery, no expandable storage, slow charging from non-Dash charge power adapters, screen low res for VR

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