The rest of the Wario land games are varying levels of good to great, but this is a completely different stratosphere. One of the best Metroidvanias I've ever played; its staggeringly creative and when you finally get the way the stages flow you'll be addicted to progress. Probably the best Game Boy game I've ever played that isn't Link's Awakening, although this one also makes you collect musical objects to escape a facsimile world.