I really can't think of anything bad to say about this game. It was a magical experience from start to finish.
The best things about it are its heart and its platforming, both of which are awesome. It is one of the few games ever with truly unique, memorable and interesting characters, the story is great, and it has a great atmosphere.
The platforming is perfect, part reaction, part puzzle solving. And the ability to rewind time removes any of the frustration that other platformers can suffer from.
The only possible complaint is that the combat isn't amazing. But its good enough, and that misses the point anyway. This isn't a combat game, the combat is just there to break up the platforming a little.
Everyone should play this game. I can't imagine anyone not loving it.