I dunno, it really needs Sonic&Knuckles, and until then, I don't think I'm gonna buy a GBA again. Sonic Advance is good, but in light of other games, it's not really pushing the boundaries of the system (and who'd ever think I'd be talking about a Nintendo system?).Great fun, and definitely a worthy buy, but just not as good as it might have been.
Summary: Good game, not Sonic&Knuckles for GBA...
Graphics: 7 (Master-system, not mega-drive)
Sound: 8 (original and best)
Gameplay: 9 (likewise)
Longevity: 7 (still got what it takes, but hardly Final Fantasy)