I just beat generations on the PS3 a while ago (after being jealous of that version due to how awful the 3DS port was) and was honestly confused on why people thought it was good... It just didn't feel "tight" enough to me. 3D sonic stages always had this awkward pacing and unless it was on boost (where you could drift or sidestep) it just felt slow and clunky.
The 2D stages weren't much better, as I felt there was a ton of stopping and starting again, similar to the awful stages in the Genesis sonic titles that made me dislike all of them but Sonic CD. (Flashbacks of terrible levels like Marble Zone, Chemical Plant zone [which for some horrid reason was REMADE in the game over a good zone like Emerald Hill or Aquatic Ruin] and Marble Garden Zone come to mind)
I feel like an oddball sonic fan, since I find the Game Gear/Master System Sonic games to be superior to the 16 Bit lineup (save for Sonic Spinball/Triple Trouble, the former of which is the worst Sonic game not on a Game Com and the latter being a game with not enough creative levels to keep me engaged.) and consider Sonic CD (2011 remake) to be the best Sonic game ever made. (Which is why I'm excited for Mania) I had a blast with Adventure 2 due to the multiplayer mode, thought Adventure 1 was OK due to the Chao garden and Tails levels being fun, and didn't care for Heroes much. I think Shadow the Hedgehog was where I lost interest in the series and games I tried out afterwards like Sonic Rush and Secret Rings just bored me. Does anyone else feel the same way I do? I honestly feel lost on how so many people thought Generations was near perfect when it felt like a slow, clunky 3D platformer to me without tight control.