My only issue is that after seeing Emerald Coast, it makes me sad to know that the 3DS game will be an exclusively side scrolling one. That quick tease of a 3D angle there doesn't help either, that's just a quick angle change for visual flair. Yes 2D is awesome, but that stage was really made for 3D IMO.
After Colors, i have renewed faith in Sega's ability to make good 3D Sonic games. Generations on consoles looks good too. I hope they eventually port the Colors engine to the 3DS or something and make an original 3D Sonic game in that style for the 3DS. That would be awesome if done right. I have to say, i'm very pleased that Sega has finally started getting back in its "groove" so to speak with Sonic.