Don't leave a voicemail, seriously.

I read the books to prepare for the show. They were a billion times more readable than Twilight, but not great. The first two, in particular, were pretty boring. I'm pretty sure this is because they focus so much on the love triangle aspect (which isn't really a love triangle, it's actually bigger, but that's how it's always labeled). The third and fourth books were actually pretty interesting because they had more plot and monsters and weren't just teen vampire romances. I've not read the newest one, because I found the ending of the fourth patently ridiculous, but I probably will eventually.

Short version: Books one and two boring romance, books three and four mostly fun adventure stories.