An amazing game with a lot of variety and replayability.
Well they become more of a reflex type of puzzle. When hit by a boss character, Wario gets sent to another part of the level. You then have to travel back and start the boss fight all over again. It is frustrating when you don't know what you're doing.
There are a lot of levels in this game, but once you beat it you'll unlock a sort-of overworld type of interface where you can clearly see how many levels there are and how many you have yet to unlock. There are a ton of secret levels and it's really fun to find them. Anyway, there's a lot of variety in these levels. You'll go through mansions, haunted mansions, caverns, trains, rivers, rooster nests, pirate ships, factories, urban areas, and... well I can't remember what else but there's more. also, each level has a treasure that you can win through a lottery type of minigame. At the end of each level there's also another minigame that you play where you guess a number, or pay lots of money to remove tiles to figure it out. When you unlock a tile, you uncover a small part of a picture. Neither of these things are worth getting this game for, but I've never been so compelled to get 100% in any other game, and I'm no completionist.
So in conclusion, this game rocks. It's one of the highest quality 2d platformers I've ever played. This game shows truly brilliant design and variety and I couldn't recommend it more.