I loved the Sonic games on the Genesis. They weren't the best things out there, but they were simple and fast. They had a certain charm to them that Sega has pretty much all but forgotten. There have been many missteps since the few good Sonic Games on the Genesis. Some of the spin-offs weren't so hot. An example of this is Sonic Spinball, but at least Spinball knew what it was. There is a whole generation of sonic games with an identity crisis.
Sonic Adventure tried too hard to be like Mario 64 and also had the unfortunate problem of showing us that when Sonic is not blazing across the screen he is a rather boring character… with rather boring friends. The introduction of Sonic's friends (beyond Tails) was a pretty bad idea. These characters, quite obviously, are not Sonic, and don't play like him. A bit of variety is generally welcome, but in this case it wasn't executed very well. The other characters levels became filler to make the game longer and more annoying.
Sonic Adventure 2 had pretty much the same problems. It was marginally better than the first, but didn't offer much improvement. That being said… I loved Sonic Adventure 2. I hated the Rose/Knuckles levels because they amounted to running/flying around an environment looking for items to find/dig up and it had a time limit. It just wasn't fun. The rest of the game was okay though… not great, but I enjoyed my time with it.
The venture into 3D was not treating Sonic well. The real problem is that when you introduce this speed demon to a 3D world you also introduce problems like level geometry and twitchy controls. Twitchy controls aren't always a bad thing. In some game it is desirable to have very precise and responsive controls, but with Sonic it just slows down the action. You can be running full speed through a level and slightly angle the thumbstick to the left and slam into a piece of level geometry bringing you to a dead stop.
Sega then tried to infuse something interesting into the sonic games like… werewolf sonic and… wait WTF. Let me start again. Sega then tried to infuse many many bad ideas into the sonic games. Granted, I had not played all of these games, but most of them I have had at least some time with. The two most recent experiences I have had with Sonic have been Sonic 4: Episode 1 (which wasn't bad, but wasn't very good either) and the Sonic Generations demo. The later has left me hopeful.
Okay, so here's the deal. Generations has 2D versions and 3D versions of levels. And they both control pretty damn well. In the full-on 3D parts, in which the camera is directly behind Sonic, the controls have been limited in a way the helps keep the game moving forward. I'm not going to sit here and explain all the controls to you because its the feel of the game the was right to me and that is going to be different for everyone. Can this hold up over an entire game? I certainly hope so. I've only played two levels in the demo. If they can be consistent and not throw in any random side characters (story is okay, but I only want to control Sonic) I think Sega may have a winner on their hands. Go check out the demo and see for yourself.