Linkin Park isn't a bad band, it's just that they are extremely overrated. They take themselves too seriously, their lyrics seem to be written by 14 year old emotional retards, and they appeal to annoying brats who have the same hardcore, shed-a-tear attitude. Instrumentally, they are fairly enjoyable and Chester Bennington can sure hammer out the notes, but so can Cher.
So, like most bands, they're nothing special, but as long as people buy their records there will be people to make threads of message boards about how much they suck. Enjoy them or don't, but don't pick fights over them.
Also, it's fun to quote Linkin Park to emos.