The irony is that fix shows a game that was very similar to what Sonic games are like now: pushing forward, doing the odd jump and trick, and never stopping.
I can't remember who it was that said it, but someone compared the original sonic games to a marble rolling around. Those Sonic games were mainly about momentum, building up speed using the scenery around you so you can find the shortest route or overcome a dead end. For example: you jump and fall into a deep pit with slopes in the Casino night zone. What do you do? You run up and down the slopes until your momentum makes you fast enough to reach back up to the top of the pit you fell in.
I think the main problem isn't so much the fact that Sonic is fast, but that he never seems to roll anymore on scenery like hills to build that speed. Now you have speed boost pads everywhere and enemies can be pushed aside by just running into them with a boost. Sonic 1 and CD relied a lot more on platforming, but in Sonic 2 and 3K you could blitz your way through a level with the right timing and momentum. If you slowed down you'd end up on another route with more platforming.
I think they have the right ideas at heart about giving you different routes based on your speed, but their execution of it still looks to be a little too automated. There's barely any physics involved, just the need to push the right buttons at the right time. I'm still glad they're at least pushing for 2D gameplay in places of Sonic Rush caliber, though. Really need a demo of this near the release.