I just set up my Fire TV and it's almost perfect for me... there are only a few niggles, some to do with XBMC, some with the Fire TV.
First, volume doesn't work. It's known, but I wish it was fixed already. Does anyone know what needs to be done to get this working? I remember a similar issue being there for the Apple TV 2, maybe the same fix can be worked on? Oddly enough, the amplification does work, so we can make the sound louder, just not less loud.
Also, I'd like to know if the home button and the microphone button can be caught.. I am one button short of having all my most used features working and I'd rather not change the forward/back buttons next to the play/pause button.
Every once in a while there's a crash, but it's rare. The plugins I've tried all work. I've upgraded to 13.1beta2 now and it's all good. The device is just so responsive after using a raspberry pi for a while now. I've had to resort to NFS shares, as my file server is OS X Mountain Lion and both SMB and AFP gave trouble/didn't work in XBMC. (on the raspbmc install I simply mounted the share in the filesystem) Advantage of NFS is that things load a lot faster.
As soon as the volume issue is fixed I'll move over, especially since my wife loves the style of the remote.
edit: I forgot.. the Fire TV does not allow all timezones, only the ones in which it is sold. I live in the Netherlands, so I cannot set my correct timezone, which means that the time is off by at least 6 hours. XBMC doesn't allow to set a separate timezone unfortunately, so I'm stuck with the wrong time. Any ideas to solve it?