Here are the games I tired so far:
Aladdin U - Playable but with some graphical glitches, good framerate
Batman Returns U - freezes after the the Mission 1 text, black screen
Bio Metal U - seems 100% playable, excellent framerate
Captain Commando - No title screen, no character select screen, but the game is playable with some framerate issues
Cool Spot - major graphical glitches, somewhat plyable, excellent framerate
Donkey Kong Country U v1.2 - Title Screen glitches, very bad slowdown, the foreground layer is missing but the game is playable
Final Fight J - loads and there is sound, but due to major graphical glitches it's unplayable
Final Fight 2 U - Seems 100% playable, excellent framerate
Final Fight 3 U - Seems 100% playable, excellent framerate
Super Mario All Stars + Mario World - only tried the first SMB, 100% playable, minor framerate issues
Teenage Mutant Ninja Turtles IV - Turtles in Time U - Seems 100% playable, excellent framerate
Bottom line, I can't believe this is an Alpha version, this is a fantastic emulator!
Also I love the Interface, I like it better this way than with some artwork or something that might make it difficult to read.