From what I've read on the Net, a lot of players dislike Toons, but I do'nt see why. The thing about Toons is that, like Exodia, newbies can make the mistake of putting them into their deck willy-nilly. If you want to use Toon Monsters, your entire deck *MUST* revolve around it. You either have a Toon deck or you don't. Anything else is a mistake.
But to answer your question,
*Toon World must be played first
* Toons are subject to everuy attack normal monsters are
*Toons can't attack the first turn they're summoned
*If Toon World is destroyed, all the other Toons are destroyed, but this doesnt' affect your life points.
*You must pay LP every time you attack with toons.
(See why your deck has to revolve around toons? You a couple of backup monster strategies, but I'd recommend only one. Two would be streaching it.)
Toons aren't for everyone, so be warned...