I'm up to the boss in World 5 and let me just say, this game is something else. It is simple in design and yet quickly becomes complicated to execute when new time rules are introduced. Your logic based puzzling skills and your platforming skills need to be honed to perfection if you want to get through this gem. The story, and surprisingly there actually is one, I can say is one of the finest i've ever seen considering you're reading off a few paragraphs at a time. The whole game is gripping, and I cannot recommend it enough. My one and only gripe is, once you do manage to beat the quest, there really isn't much else to do but a speed run for that last achievement.
BTW: This game plays great homage to both Donkay Kong and Super Mario Bros. Pirahhna plants, goomba like guys, a dinosaur(Yoshi inspired) that always lets you know the princess is in another castle and a Donkey Kong-like layout in World 4 in one of the rooms.