I'm really mixed on this question: Is this game good?
Yes and nah.
Pros:
-The Chao Garden was undoubtedly one of the best things in this game
-It had an interesting story.
-It had excellent bosses.
Cons:
-Glitches, like in Shadow the hedgehog and most of the games released at the time.
-Graphics are awful, period.
I would honestly recommend you to watch Sonic X instead of bothering playing this.
I will also add that this game has spawned a group of very awful and scary fanboys that call themselves the Sonic Adventure fans. Saying their names is as cursed as saying "Voldemort" or "Maltazard".
Here it goes: Al Jerico (The Den, Mischivous Yroo, aurtis89), DarkSonic180 (SonicTeam765), Monkey D Luffy, Xcalibur or even Hunter. Remember those names it may save your life, but never say them out loud.