I have had limited time with the OUYA but here is a quick and dirty review.
It's small and silent.
The UI is pretty slow. Boot time is around 10-15 seconds but there is kinda a hitch in it's giddy up.
DL'ing is pretty damn slow. Maybe because it was running on wireless. Maybe not. I won't know till I use the ethernet port (yay for wired!)
Limited selection of software. I expected this so it doesn't really bother me. I dl'd a dubwars game that was decent and a snes emu.