Now, I've always been a fan of Wario Land, but my understanding of the series recently changed when I realized that the whole series is Nintendo's Self-Parody of Super Mario Bros., in the form of a Fractured Fairy Tale. The kind, heroic and friendly Mario is replaced with a greedy, selfish, brute whose appearance is an exaggeration of all of Mario's features (big nose, curly mustashe, ect.) The enemies are more evil, and while Mario journeys across the Mushroom Kingdom to resuce Princess Peach and save the world, Wario only does heroic deeds when he sees an oppurtunity to get rich doing so. Wario does things such as set himself on fire and break through stone with his head to progress, which is quite different than Mario's athleticism and jumping on top of enemies. Brilliant! -Dr Furball
I used to dislike Wario's toilet humour. Then I realized it: Mario likes MUshrooms and wario likes WAshrooms.
The reason Wario is slower than mario is not only because he is fatter, but because his games should be played slower with more focus on exploration.