People are mainly complaining about them using the boost formula again because this game looks closer to a regression in the gameplay. They remove quickstep and drifting, inherent parts of the formula there since it's introduction. The whole reason boost Sonic controls so badly is so much of the challenge comes in maneuvering Sonic, eg.) quick step and drifting. The animations as well as player control also happen to look noticeably more stiff than Unleashed, Colors, or Generations. People are mainly complaining about the custom character because it doesn't really add anything to the game. It's just kind of there and looks cheap in a R&D standpoint. People are mainly complaining about Green Hill because it's basically Generations Green Hill but worse, meanwhile Mania has a remix of Green Hill with its own set of tropes. People also complained about Green Hill in Mania, just not to the same extent because it's not as bad of an offender. People are mainly complaining about them not changing the boost mechanics too much because we got 3 3D boost games with very small changes in the formula. Most here also agreed boost gameplay has potential, they're just not reaching it. Don't take this personally, but don't try to attach connotations to genuine critique people have about this game and assume you know their motive. If there's one guy that doesn't like the music of this game, doesn't mean they really want that nostalgia pandering. They could genuinely not like the music, which isn't surprising because the music in Sonic Forces is a much different style than previous games. Ohtani has a large variety of styles in his belt.