The Fire phone is Amazon's first smartphone and it has a couple of unique features including special front-facing cameras which create a pseudo-3D effect throughout the operating system. There's also Firefly which uses the camera to recognise text and objects, allowing you to quickly go to a website, make a phone call or buy a product you've seen. See also: Best smartphones 2014
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Amazon Fire phone review: hardware design
The phone is reminiscent of the iPhone 4, since there are glass panels front and rear. There's also a top-mounted headphone socket and sleep/wake button.
It's the same size at the new iPhone 6, though, with a 4.7in screen. Resolution is slightly lower but it's a great screen.
There are no buttons on the right-hand side but on the left are volume and a dedicated button for the camera and Firefly.
At the bottom is microUSB for easy charging and synching, and stereo speakers hide behind grilles on the top and bottom edges.
Amazon Fire phone review: software
The Fire phone runs a similar operating system to Amazon's Kindle Fire tablets and is also based on Android.
If you've used one of Amazon's tablets, you'll be right at home since navigation is very similar. You get a carousel of recent apps and content, and you swipe upwards to see all of the apps. Swiping down from the top brings up a kind of control centre and notification area.
Selecting an item from the carousel displays relevant options below it, and is one of Fire OS's best features.
What's not quite as obvious is that you can swipe in from the right-hand side and left-hand side to display different menus and information, and they change depending on the app you're using. If you're on the home screen you get a menu for quickly jumping to your music, videos, photos, apps, games, documents.
Almost every option gives you some way to buy content from Amazon, including Shop which gives you a smartphone-friendly version of Amazon.co.uk
While Amazon's selection of books and music rivals the best out there, it's a different story with apps and games. The selection is much better than it was a year or two ago, but it still isn't as good as the Google Play store and because this isn't an Android phone, there is of course no Google play store, nor any official Google apps such as Maps, Gmail or YouTube.
Firefly is exclusive to the Fire phone at the moment, and could well prove a useful feature. It works well at detecting printed web addresses, letting you tap to launch the browser and load the site.
It can also music, movies, TV episodes, books, games, DVDs and many products with a barcode. In our tests, it failed to identify any movies or TV shows, though. With products, there was often a match in Amazon's shop.
We're less convinced about Dynamic Perspective. From the wacky 3D lock screens to app icons and even toggle switches, Amazon has tried to incorporate 3D just about everywhere.
It works is by sensing the position of your head relative to the screen, so moving your head or tilting the smartphone itself changes what you see on screen. Even some text is rendered in 3D, which can look blurry and is quite off-putting.
With no Google Maps, Amazon has made with its own maps app which also supports Dynamic Perspective. There are 3D outlines of buildings, but only a few landmarks have textures. You can get driving and walking directions, as well as for public transport.
Amazon Fire phone review: One-handed gestures
Possibly our favourite feature of the Fire phone is one-handed gestures. A quick tilt left or right brings up the respective menu, and these can also be hidden by tilting the other way.
Another gesture is auto-scrolling. This works by tilting the phone up or down slightly. The more you tip, the faster a web page or menu scrolls.
Rotating the phone to the right displays the control centre offering quick access to the torch, Mayday - Amazon's live tech support service - and notifications.
Finally, there's Peek, which shows extra information when you very slightly tilt the Fire phone. This can bring up extra information, but when browsing Amazon's shop you can see a larger image of the item.
Amazon Fire phone review: cameras
Amazon hasn't skimped on the main camera, as it has a 13Mp sensor and optical stabilisation, and there's 2.1Mp camera at the front.
Photo quality is pretty good, and the stabilisation really shows in video clips, which are rock steady. The camera app includes HDR and there's a strange Lenticular mode where you can take up to 11 photos from slightly different angles, resulting in a stilted animation which you can only view on the phone itself.
Amazon Fire phone review: verdict
Even though you can get it free on contract, the Fire phone isn't as cheap as we had expected. For a similar contract price, or even when bought SIM-free, you could have a flagship Android phone such as the LG G3. If you're comparing specifications, the Fire phone looks distinctly mid-range.
Amazon is throwing in a year's Prime membership if you buy a Fire phone before 2015 which sweetens the deal, but it doesn't change the fact that you still have to live in Amazon's walled garden.
It's a lovely garden, but we think it will require an even lower price to persuade people to lock themselves in.