much better overall than the first game but still has plenty of hiccups. i really hate how they've changed the special stage system, special stages being tied to checkpoints makes the player backtrack a lot which totally fucks the pace of these levels. the special stages themselves are also not very good and a lot harder than in 1. special stages being like this also means that collecting rings doesn't feel as rewarding, since they're going to disappear if you complete a special stage objective
if you ignore the existence of the chaos emeralds, though, this game is pretty fun! the level design is more freeform and forgiving than sonic 1. generally if you fall down or miss a jump in this game, you'll just be put on a different path rather than losing momentum entirely or dying, which is pretty cool! the final stretch is a lot weaker than the rest of the game, but when the whole game is about an hour and a half long, it's hard to get too upset.