True to Sonic's 2D roots.
Gameplay:
Sonic Advance 3 incorporates a "partner" system. You must choose a leader as your main character, and a sidekick to follow you throughout the level. Depending on the match-up made, the leading character will get special moves. If you pair Sonic with Tails, then Tails will be able to hold Sonic while he flies for a brief period. If you pair Sonic and Knuckles, Knuckles will be able to throw Sonic towards enemies as an attack.
For those who played Sonic Adventure on the Dreamcast, or its GameCube remake Sonic Adventure DX: Director's Cut, you are familiar with "adventure fields." Sonic Advance 3 has "hubs" which are similar to Sonic Adventure's adventure fields. There are three portals in each hub leading to action stages, as well as bonus mini-games and one boss fight once all three action stages have been completed.
The actual gameplay itself is similar every other Sonic Advance game, which relates to the original Genesis games.
Graphics:
Fluid animation and impressive backgrounds give Sonic Advance 3 the upper hand on many GameBoy Advance games.
Sound:
Sonic Advance 3 actually has several voice-acting moments. Eggman will repeatedly shout during battles, "You're going to pay for this," and Sonic will yell or grunt whenever he is hit. And the music will definitely take you back so far...so far...so far...
Value:
There are medals to collect and multiplayer for your friends, and the fun factor increases the game's value dramatically.
Sonic Advance 3 is truer to its 2D than any other game before it. Sonic fans will want this game; it is truly a must-buy.