They've totally fucked themselves with their new album, because they let their guitarist write the lyrics, and they're pretty retarded and derivative. However, I'm all for not jumping on band-wagons: the first two albums are ok. *gasp* Remember that, when people call them 'experimental' or 'innovative' that they're part of the whole alt-rock/nu-metal scene (the same one that makes Tool look progressive), and really, they aren't actually copying anyone. Their lyrics (used) to be of a reasonable standard, their guitar isn't bad, and they do have a reasonable political consciousness (ironically, the thing they've tried to do most is promote awareness of the Armenian genocide, and, well, ask any of their fans about that...). They're nothing special, quite cool when you're 14 though.
Also, I doubt Slipknot are copying Mr. Bungle. Insane Clown Posse, however (the ones who changed their name from 'Inner City Posse' and started wearing evil clown makeup whilst Bungle were at the height of their popularity), more likely. Though ironically Mate.Feed.Kill.Repeat is probably inspired a bit by Mr. Bungle. (they dropped their eclecticism pretty much entirely after that however.)