This isn't a full review, but I wanted to mention a few things about the much misaligned "3D useless gimmick."
It isn't a gimmick and it's pretty useful.
Ok first, the "home screen" with 3D icons. Ok, that's a gimmick. But the face tracking goes past that.
There are cool little uses like the status bar not showing unless the user slightly turns the phone. Another is showing extra info that would look cluttered normally. Mainly text labels and such. So you can work with a clean interface but if you need to see the labels, simply slightly turn the phone horizontally and the text shows. It's a neat concept.
There are other HUGE interface concepts like their home screen. It's called the carousel and it's a live "recently used" list that scrolls horizontally. The cool thin is it shows the most recent used or live items under each icon. So you can swipe though the carousel and see recent photos, email, messages, even the menu selections you used on the "Settings" app. It's a smart idea and it much faster than widgets.
Another cool thing is the three screens concept. Each app has three screens; the main center one, the once on the right that show often used items for the app, and the one on the left that shows a menu. A quick flick brings down a "system's quick menu" for things lie airplane mode, flashlight, and such.
It's has a nice camera and firefly.
And to be honest, the 3D lock screens are cool to look at and it's a nice difference to have.
The Fire is in no way worth what Amazon wanted when it was released. But for the $130 I paid, including a years extension of Prime, it's a steal of a deal.
It's a good phone.