The Game Boy Advanced is a great handheld console, and in my opinion, second to only the Nintendo DS. This is no wonder though, as the Game Boy Advanced uses a 32 bit RISC CPU, the ARM7TDMI which is a pretty robust CPU for a handheld console. The Game Boy Advance is roughly comparable to the Snes, except all in the palm of your hand, although obviously the capabilities of the GBA are limited compared to full size consoles that plugin in to a TV. The only real drawback that I find with the GBA is the screen resolution, which is 240x160 pixels, not all that far removed from older consoles like the Nes, but non the less, smaller.
Sometimes called VBA, this emulator is close to my heart, as it is open source, something I find very appealing. It was originally written by the author, "Forgotten", but has been passed onto other authors since then and has been forked into various projects. The emulator itself is very useful to emulator developers as it features a good debugger and tile viewer, as well as various other debugging functions.
The compatibilty rate of the games is very high as far as I can see, I haven't yet seen a single bug in any game I've played, let alone any game not playing. Sound is supported and sounds high quality.
Anyway, i haven't got much to say other than this emulator is awesome and deserves to be played. Games I would recommend are Contra Advanced and Mario Kart - Super Circuit, these games are my favourites.
Hope you enjoy this fantastic emulator
Here's 100 GBA games :)