SEGA hasn't released a decent Sonic game in a while (or one that is actually worth playing), and if you're looking for that, you won't find it here.
Ever since the Dreamcast's Sonic Adventure, SEGA has had many problems releasing a new Sonic experience for all of the Sonic Fanboys, and this one is no exception. Basically Sonic Battle was a failed attempt to bring a multiplayer fighting game (much like SSBM) to the GBA. At first glance this title may look appealing, but really it isn't more than mediocore.
The graphics feature 2D pixelated sprites, on a full 3D engine backround. The various stages look quite amazing on the GBA, but too bad the charcters couldn't be in full 3D. After a while, you will notice that the stages aren't anything more than different rectangular shaped rooms. The sound in the game was below average, or you could say horrible, and the music will become annoying just after 5 minutes of playing.
But, beleive it or not, that is not what made this game so horrible. It was the controls and gameplay. The controls were actually nicely laid out on the GBA, but they are soooo slow, and not responsive most of the time. Also the gameplay is nothing more than going around different characters, and collecting cards so that you can customize your Chaos emerald powered robot. Oh, and the storyline looks like a couple of third graders made it.
And after saying that, I DON'T HIGHLY RECOMMEND this game. You might like it more that I do, and you might disagree with me, but just for the record I am a Sonic fan, and I found nothing behind the repetitive gameplay, so I give Sonic Battle 2 out of 5 Stars.