Something about one of the peices of music:
Someone on YouTube pointed out that Modern Sonic wouldn't need invincibility because he has boost. They thought that must mean the game is hard. I don't think thats it.
They talk about the game celebrating 3 eras of Sonic. Classic, Dreamcast and Modern. So I'm thinking Modern Sonic wont just have his Unleashed "pretty much on rails" style levels. I'm think he will also have Sonic Adventure 2 style levels.
A cool little thing about the demo. When you run, Sonic kicks up dust behind him. If you run and stop, the dust keeps going.
When you get to the double backwards S shaped tunnels (the one that you enter after you pass the two Krabmeats and the flying enemy), enter them and then turn around and spindash back up them. When Sonic comes out the top one, he'll run into a wall and stop but you still see the dust carry on.
It's a small detail but I like it for some reason.