Hmm couldn't find the thread for this. I think there may be one in the depths of the forum somewhere. Max got this for Christmas, so naturally I've been helping him out a little on it and having the odd go myself.
Fundamentally this seems very similar to the Sonic Generations demo, but they've mashed together the side scrolling and into the screen stuff. It looks absolutely lovely.
There are a couple of niggles, but fundamentally what they've done in Sonic Clours and by extension Generations is come up with a template for a 3D sonic game that works really well and is a lot of fun to play. I hope that Sega stick with the boost, jump, slide control system they have here for future releases.
Niggles wise the difficulty seems a bit hit and miss based on watching Max play. Some levels he can clear without any help, whilst others have some really tricky sections in that he finds impossible. On one level he got stuck down a pit with no apparent means of escape and we had to restart the level, which was odd. Also I haven't been able to figure out the control for the laser powerup - selecting the direction seems a bit hit and miss, but this is probably me being an idiot.
It's a score chasing game at heart, with S ranks to win. Be prepared to replay levels as new powerups become available. Many of these are necessary to score the 5 red tokens on each level. this is fine though as the game is an absolute joy to play.

Yeah its fine isn't it, the final 10% or 20% seem to be missing that level of polish or consistent-ness to tie it all together. All the issues seem to be fundamental Sonic Team issues where they just don't ever seem to understand what the problem is y'know?
Never had a problem with the powerups, but I never bothered with the chasing of ranks since the guts of these games seem to not actually exist, some of the levels just degenerate into slack madness so cleaning the whole title would be psychologically impossible to even start.
Can't remember any standout levels (like the first one in Rings)?
I see your point the first level in Rings is very memorable, but I think there are some pretty impressive levels in here too.
The first Act of Starlight Carnival is pretty stonking. Sonic starts upside down then you're running on a road that is being built in space ahead of you and destroyed behind you. Then you're homing attacking across to a giant spaceship, some indoors stuff, before free falling into the screen through a fleet of ships coming out of hyperspace. It's completely fantastic!