I'm definitely enjoying the game so far, although it definitely doesn't feel as rapturous for me as it is for some folks here so far.
I really like the controls, and the overall gameplay premise. I'm getting into the levels where you switch between flying and running and it's great. The game has a Sonic-ish sense of momentum that I really like.
What I don't like so far: the briefness of the levels coupled with the amount of menus and cutscens between each level. I can blast through a stage in a minute or two; after that, mashing through the menus and story stuff (yes, I know you can skip it, but it's still there as a roadblock) is a bit of a pain, especially considering the story hasn't grabbed me in the slightest so far. This really feels like a game that should have just given a quick text crawl to set the stage and then let you loose on the levels, arcade style.
I'm also not a big fan of the presentation, especially the running animation. I like the character designs on their own, but the visuals/music are a bit bland otherwise.
Will stick with it though, it's a neat little game so far.