I've been thinking of giving Sonic 4 a try just so I can understand some of the consternation. I heard episode 2 is a little better than 1
Episode 2 is infinitely better than 1, but that's not saying much. It's certainly much easier on the eyes, but not much better on the ears. Also the level design is still somewhat shoddy, and most levels still retain the problem of feeling ripped off from earlier Sonic games rather than being new. It's not bad though, just kind of forgettable once you finish.