Third in the Twilight series by Stephenie Meyer...
First off... same issues as I had with book the second... so I shan't rehash them here. I'll just do a little plot business for my own memory.
The bad guys from the first book are back and want revenge, so the vamps and the were have to defend Bella. Which involves them working together which they're programmed not to do.
And there's this whole "Bella has to choose" thing going on through most of it, which makes the above mentioned issues more annoying. The guy who's more believable and interesting is of course the one that she isn't being written to want. It's frustrating, the author is clearly capable of writing an interesting three-dimensional guy, so why aren't both guys written that way?