I'd like to believe that this game is indeed a fun one, but so flawed it broke the bases. Knuckles/Rouge hunting stages break the flow by a lot, due of a combination of the rather cryptic radar and the way the collectibles were hidden. For an average player, it's very possible that these missions last for far longer than a few minutes because they're having hard time finding anything. Doesn't help that most levels look bland, aside the one with pumpkin heads with a great music that comes with it. Great concept, poor execution, I guess.
Tails/Eggman stages are still dampening the flow, but are nowhere as bad as the aforementioned hunting stages. Most of the time, it's about mindlessly pressing A button over and over again to shoot at enemies, therefore trivializing pretty much any interest of the gameplay. The annoying "ding" laser sound effect might even drive some people insane, and the level design is meh in general. At least, they tend to be over quick enough and I never see them after this game.
I have almost nothing to say about Sonic/Shadow stages. The level design is an improvement over the predecessor, as it's much more fun to traverse these stages amazingly fast. Too bad there aren't as many of these levels. These alone would make Sonic Adventure 2 another real classic from the franchise.
It's funny how Chaos Garden is apparently considered to be among the best parts of the game. That mode could've made SEGA considering developing a game heavily influenced from it.
Had a lot of fun playing the game as a children, but coming back to it as an older gamer won't feel the same anymore. It just never will age well thanks to numerous flaws that'll rear their ugly heads.
