This is very possibly the worst Sonic game I have ever played, and I've played nearly all of them.
Since the Sonic series began the thing that allured me was the Sonic speed. Even though I didn't have a Genesis I was envious anyone who did, just because of Sonic the Hedgehog.
When I got a Dreamcast of my own my very first game was Sonic Adventure 2. While I was a little disappointed that there wasn't as much Sonic playing (and I guess to a lesser extent Shadow) as I had previously thought, I still enjoyed the levels where you DID play as Sonic.
Fast forward to Sonic Heros, the next big from Sonic and friends, where they work together, and lo and behold you have FOUR different teams to chose from. WILD! The excitement ended about ten minutes into the game.
I HATE having to use the other characters, specifically the flying characters who's attacks seemed to have been made up in 10 seconds when they couldn't think of a good real attack. They just throw one of their dangling friends at an enemy, but no, it doesn't actually destroy the enemy most times, no it just stuns them. Pretty much the only time the flying character is useful is when you NEED to fly. Otherwise using them is just a waste of time.
Atleast the other characters have uses beyond going fast.
The speed and power characters (Sonic and Knuckles) can both take out enemies fairly well. Knuckles better than Sonic, I'll usually switch to Knuckles if there is enough enemies to be worried about.
Now the controls and camera angles are what REALLY gets me. It's far too easy to make a mistake that will just screw you over, push a single button and you've rolled off the edge to your death, when you actually wanted to just hit the box.
The one thing I DID enjoy over SA2 was that Sega finally wised up just a little about camera angles in that you can rotate them more easily, but still there are times when I can't see what needs to be done, and it's very frustrating.
The game says how the levels are different depending on which team you pick, with my experience the differences of minimal at best, so you basically playing the same level four times.
I would not recommend this game to ANYONE and would avoid it like the plague. If I can save anyone's money from this atrocity my job here is done.