I never posted my impressions here, copy and paste from neogaf
"Finally got to play the demo
Modern Sonic is AMAZING
hes tons better then Sonic Unleashed, hes better then Colors
I thought Green Hill Zone was going to be a super easy level, it just looked like a mainly boost to win level in the videos I saw of it, but it's not true. It actually takes skill to pull off some of the upper paths. Took me a while <3 to get good enough I love it so much.
It's got that exhilarating feel of Sonic Unleashed when going at massive speeds, but if you aren't careful you can easily screw yourself over and unlike in Unleashed it's not just sending you into traps to kill you. If you try to boost through the whole level you just end up screwing yourself over in a way that really slows you down. You can't boost to win unless you know what you are doing. '
I'm still not bored of Modern Sonic yet and ive played his level so many times. Much more then I can say for either the first level of Unleashed or Colors. I also agree with anyone who thinks Modern Sonic GHZ has more paths then classic Sonic GHZ.
Did I mention that pulling off that drift is freaking awesome? Oh yeah... it is! Pulling off tricks is a great feeling too.
So just remember, what you see isn't what you get necessarily, and I mean that in a good way! After what I've heard about the later modern levels being full of 3D platforming, and knowing City Escape has much more substance then GHZ.. I seriously can't wait to play more. I still got a lot of perfecting I need to do for modern Sonic GHZ. SO yeah.... good times ahead!"
my current best time as of today is 1:57, having a really hard time getting past that.. but yeah.. really love modern Sonic in this game <3