I have on my GP32 and am playing with
GPscumm156: very stable, Sam n Max a little slugish, others ok.
GPdoom: very stable with doom II commercial version and a bunch of modded WADs.
GPengine: really really good, plays a ton of roms, not all, but tons.
Osnes9xgp: runs lots of games stablely
LittleJohn Nes: perfect, I like the screen stretching option, looks a little distorted but I like the way it fills the screen.
I have others installed but haven't really ran them hard yet.
I like the Jpeg viewer. I can load a ton of pictures on the GP32 and looks much better than the crappy 1.5 inch screens of the camera itself.
Hope this helps any.