Amazon stepped into the smartphone race this afternoon with the unveiling of the Fire Phone, its very first attempt at building a smartphone. By most outward appearances, it's a strong first attempt: the 4.7-inch phone has a simple black body, a 720p display, a fast 13-megapixel camera, and plenty of processing power to keep things moving. Naturally, it's running a version of Fire OS, the highly modified version of Android that Amazon has been using on its Kindle Fire tablets for a couple years now.

That's all pretty standard fare, but there's one big difference here: the Fire Phone's interface changes based on how you're looking at it and how you orient the device. Amazon calls the feature "Dynamic Perspective," which basically means that some apps on the phone will have a three-dimensional depth to them, and tilting the phone will let you peer around edges, just as you can with real objects. It's miles away from the accelerometer-based gimmicks we've seen on older 3D phones. In fact, it's not really even fair to call it 3D in the traditional sense. You're looking around objects, but there's no attempt to make stuff pop off the screen. It's refined, but we'll have to really use the phone for a long time to know if it's something we'd actually want to use.