This game has some great things in its favor. It is extremely creative, graphically beautiful and fun to play with some very unique puzzles to solve. The ability to rewind time eliminates the frustration of many games, where you have to replay from the beginning of a level when you fail. It also provides for some of the best puzzles I've ever seen!
That said, it suffers from some very serious problems. First and foremost, it's way too short. I'm disappointed to find that the $15 I spent yesterday only lasted me until today. And the replay value is very limited... once you've solved the puzzles, the only thing to do is to run the levels faster. That sort of thing - trying over and over to get your timing just exactly perfect - is something I find to be mind-numbingly boring and frustrating rather than fun.
Some of the puzzles were also a bit more difficult than they could have been with some basic instructions... yet the only documentation consisted of what the keys were for movement and jumping. There's a lot of experimentation involved with learning about what you can and can't do. I won't post spoilers, but I will say that each level can be solved before going to the next... for a long time, I thought maybe I needed to gain some power or item and come back to solve some of them, and that is not the case.
More annoyingly, I find my $15 wasted even worse because I can't get to the ending. I'm right there, on the last level, and not far from the end according to walkthroughs... but because the ending requires such perfectly precise timing from the very beginning of the level, I can't manage to finish it after over an hour of trying. Even with the ability to rewind time, so that I can try over and over at the spot I'm stuck without having to replay from the beginning of the level every time I fail, I still can't do it. Since it has reached the point where trying is not even remotely fun, I've given up. I guess I'll just have to live without seeing the end.
That also won't be much of a hardship, as the storytelling is surreal and confusing to the point of not being interesting. So missing the end of a story I don't really get isn't the end of the world.
So, long story short... the puzzles and gameplay are extremely creative and can be very fun, but this game also has some pretty big frustrations.