A lot has been written about the Fire TV, with most of it emphasizing the media aspects. I gave it a 5 star review the first week I had it, and would still give it the same.
I also bought a controller at the same time, thinking it would be great to play games that were engaging but not expensive, fun but not so immersive they take over your life.
Amazon provided a controller for review purposes as well, meaning I now have 2. What I like about it is it really does provided added enjoyment to the Fire TV. If you are at all interested in the gaming side of it, then getting a controller is a very worthwhile step. That being said, there's nothing about this particular controller that stands out and indeed the price is a bit high for the features.
If you have any experience with game consoles over the last decade, or more, this controller will feel very familiar. It's a bit larger and more angular than the XBox 360 controller, but the button setup is almost exactly the same. I find that after playing a while my hand starts falling asleep, no doubt because it is less rounded and so puts more pressure on the hand.
Bluetooth controlled, and very responsive, so it definitely works well. But no added features or capabilities. No rumbling or headphone/microphone inputs (which would be good for potential headsets for multiplayer games). I don't care much about those but I would have really liked motion detection of some kind, which is standard in tablets and smartphones, and as such used by some android games. That would have justified the higher price.
As far as games, the library of really good games is small. Sev Zero is indeed pretty fun, and when I bought the controller I got that and 1000 amazon credits as a "free" bonus. The hope, and expectation, is that the game library will grow not only in size (there really are a lot of games) and in depth, with high quality games making the controller even more necessary.