I got a few of these for my latest RetroPie build, and love them. 8Bitdo stuff in general is very good in general (works well via BT, solid construction), but this is my favorite. It still has the retro vibes but has enough functionality thanks to the two analog joysticks and 4 bumper buttons to perform well with NES classics all the way up to PS2 and N64 games. The massdrop pricing on these is great as well, highly recommend these little guys.
PhatfredI can tell you that retropie on raspberry Pi is very easy to install, and runs absolutely amazing on my Pi3. It can run up to PS1 and PSP games, (Though PSP can hiccup a bit.)