I bought the full version of this a couple weeks ago. It took me about two tries to find a working gba_bios file. I think I saved it separately from my roms or something. But so far the emulator is working fine on my Droid with no real problems with the program.
But some of the roms are off. Most of the gameshark or action replay roms I have found will not work, beacause they need their switch turned ON. I did fine Codebreaker, and it works, but I can't get a game to load with it, since I don't think the emulator can support more than 1 rom at a time, maybe.
But the GBAoid is definitely worth the few bucks to support the author of it.