Actually, there definitely was quite a lot frustrating about this book and pretty much all of it can be summed up in one word: Miranda. I hate just about everything about her. After she's turned into a vampire princess against her will, she just rolls with it. She happily eats people and calls the creepy, power-mad vampire who turned her Father, because that helps him fulfill his delusion. Miranda is entirely vapid, conceited and selfish.
Smith tries to set her up as an object of pity by showing her friend Lucy's devotion to her, by showing Zachary's love for her, and by suggesting she had a rough home life. The only one of these that's working for me is Lucy. Miranda's fate doesn't sadden me, but her best friend's does, desperately hoping that her friend has not died because of her desire to flirt. Zachary I actually find to be a somewhat interesting character, but his love for her is both creepy (what with the whole guardian angel, watching her grow from a child to a teen, watching her sleep thing) and ridiculous (she sucks [punned!], so why love her?). And, as for her rough home life, her parents got a divorce. Not to say that that is not painful, but her mother still loves her, and her dad, though distant, buys her awesome presents (now who's selfish? haha).
If you like Maggie Stiefvater's books, you may want to give Cynthia Leitich Smith a try. They have a lot of commonalities, I feel. Both have really clever ideas for paranormal YA romances and both write incredibly obnoxious female main characters. With both books I've read so far, I feel like the stories would have been so much more interesting had they focused on the male characters more.