My opinion about Wizard101 is that Wizard101 is an addicting game, to be honest. When I first played Wizard101 I thought: "Oh, this is cool" or something like that. But after reaching the third world, the game becomes quite boring actually.
So, because the game is boring, KI (KingIsles the game maker) added some new things: Cheating Bosses. Cheating Bosses are bosses who didn't "follow rules". They challenged players and they can do something wizards cannot do.
But as wizards reached the final worlds (Khrysalis, Azteca, Avalon), the Cheating Bosses also become boring. The games are actually still fun. Can anyone imagine that? Fun but boring? Well, the quests and NPC were interesting, but boss fights are too ordinary. But many people are still playing that game.