I don't like the visual style or the level design. It just doesn't have the same feeling as the original Sonic games, but then that's a difference I'd expect when comparing a team of '80s/'90s Japanese veterans to a Western Indie team of today
The visual design looks incredible to me, honestly. It's very similar to the busy, vibrant, and sort of abstract style of Sonic CD. Sonic CD always felt like an evolution of Sonic 1's visual style. Sonic 2 and 3 were a tad more grounded in reality, to an extent.
I can understand being a tad concerned about the level design, as some of it does look like it could potentially frustrate less experienced players and confuse them, but as a whole it looks very creative and ripe for players to experiment.
We've all got our opinions... but...
Sonic 2 improves on nearly everything Sonic 1 did. Better, more consistent level design (that plays to the strengths of Sonic), more levels, an actual reward for nabbing the Chaos Emeralds, Tails, etc.
I can sort of understand if you preferred Sonic 2 over 3&K since 3&K has a bigger emphasis on exploration that you may not be interested in but Sonic 2 is just straight up better than Sonic 1. It's similar to how SMB3 took what SMB1 did and improved on it in nearly every aspect.
While typing that list, I was gonna throw Adventure 2 on there, but put an asterisk on it. There's are many things I like about the game, but has some glaring glitches, and all of its play styles may not mesh well with everyone.
Yeah, I'd never say Adventure 2 (or 1) are great games. They have humongous flaws that for many will be hard to overlook and I don't blame people if they don't like them. They certainly aren't terrible games, though. Adventure 1 was very ambitious for it's time (a little too ambitious) and Adventure 2 tried to fix a lot of Adventure 1's shortcomings (no wasting time in hub worlds, removing fishing and Amy gameplay, etc) but still lacked polish and not all of its ideas were good ones (the more dark and realistic tone, mech gameplay being clunkier, etc).