Let me fill you in with some perspective. I'm someone who used to HATE this game. I hated the controls, the stage gimmicks, the combat, the obnoxious casino levels, the fact that you had to play the game essentially 4 times to fully beat it, etc. I put it down for years after I beat it and that was the end of it.

But years later when I returned to it, I was willing to try and put in the effort to work at getting better at this game's controls and mechanics, learn speedrun tech, all that jazz. I wanted to see what others saw in this game, and low and behold, after putting a lot of time in to improve at this game, Sonic Heroes has quickly become a game I despised, to one of my favorite Sonic games of all time.

I think we should start with the control issue, yes speed formation is slippery and finnicky on a first playthrough, but you have other styles to switch to, power and flight. Both of these are slower and have better traction so it's easier to get a handling on the terrain, but once you DO master speed formation, the movement abilities and cool tricks you can do is second to none. You can rocket accel up slopes and ramps to bypass fan gliding sections, use tornado jump as a means of a double jump, slide off a platform and jump before the animation ends to get crazy distance in the air, combining rocket accel with Tails or Knuckles to get crazy distance, it's super satisfying to pull off.

And in terms of the combat, I'll be the first to say that while it isn't amazing, I think it's very interesting and fun to use for a platformer. You have different means of attacks and different strategies for different enemies (like flying metal enemies needing to be stunned by Tails before it can be taken care of by Knuckles). Knuckles straight punches are super effective at clearing hoards of enemies super fast at the cost of being pretty slippery, but you also have the much safer but slower fireball dunk to take care of enemies this way. Faster combat being a trade off for looser control, while the safer option is more slow. Risk and reward design like this is present all throughout Heroes. Another example of this is using the more unwieldy rocket accel to take off shields and flip the turtle enemies (or even use poles) without slowing down versus stopping to use the whirlwind attack and dealing less damage overall. Leveling up throughout a stage also increases your combat effectiveness tenfold; each character can level up 3 times in a stage, with all levels being reset if you die, rewarding skillful play if you keep your characters leveled throughout. max level speed or flight characters can clear a room much much faster than they originally could against Power, with Power formation absolutely slaughtering giant brutes at max level. And then you get team blast which nukes the entire area you're in killing all enemies on screen, and can also have different effects depending on the team you pick. It's usually best to save Team Blast for when you really need it (such as an area full of enemies with a tough bigger brute character with armor), rather than using it whenever you feel like it.

The levels themselves are a blast to traverse through as well. The levels are expansive with different paths and shortcuts to take with a decent length to each level without any of them really overstaying their welcome. Combine this with the excellent movement mechanics in conjunction with the combat and you have a marvelous high speed platformer.

It's not all perfect though, certain issues I had with the game then still are prevalent now. The casino stages absolutely blow. I don't know who was in charge of the pinball physics needed to go up the tables or steer in Bingo Highway but they completely failed at it. The physics are just all over the place and fluctuate on a whim, often times I can be holding a direction and Sonic just refuses to go in that direction and ends up falling to his death. These can make the pinball sections take forever as you can be constantly stuck on the table because the controls just refuse to work with you at all. The special stages are also still awful. The act of getting to them is fine enough (collecting a key locked in a cage and keeping it throughout the level without getting hurt) but the special stage itself controls like garbage and it's near impossible to see obstacles coming in time while moving at such a ridiculous speed. Team Chaotix as a whole is pretty unremarkable as well, with their gameplay being mission focused. Easily the worst out of all the other teams. The game forcing you to play it multiple times can be a turn off but since I love the core gameplay and level design I'm at least somewhat willing to look past this.

Overall I get why people can not like this game I really do. And I also understand if taking the time to master the controls and mechanics and really "git gud" at the game isn't a guarantee you'll like it (heck I did the same for DMC4 and Sonic Unleashed and I still hate both those games), but I employ you to at the very least give it another look at with everything I said in mind. Sonic Heroes is a very weird but extremely rewarding experience. (Also you don't have that stupid Chao raising crap and the upgrade system is gone + no mechs so I consider this better than SA2 by default. Maybe one day I'll try and 100% the game and get Super Hard Mode.)