I actually just picked it up a few days ago and it's better than I was expecting. The Sonic Cycle has been especially brutal in recent years, so my expectations were more or less in the toilet. I'll echo others' sentiments that sudden, unexpected death traps feel pretty prevalent, especially in later stages. But overall, I don't feel "bad" about the purchase. It's hard to say what I expect out of a Sonic game these days -- the last portable Sonic game I played was the second GBA entry -- but Generations on 3DS is good enough that I'll finish it and likely do some of the extra stuff (missions) after.
Something I'm wondering through is how different is the console version? Would I be basically playing the same game if I picked that up on Xbox 360 at some point down the line?