Hmm, somewhere between 3 and 4 stars for me. 
 The main protagonist is a bit of a pain, and admits it freely. Her obnoxiousness and intractability become a major point of the plot, as she realizes the mistakes she's made that has caused so much strain to her friends, family, and herself. 
 What's rather refreshing for me is the feel of all the characters, despite the usual high school drama and romance. There's a variety to her friends, from dorky chubby girls to popular girls to stable friends to dumb jocks. Even the girl who pops up as the last minute antagonist manages to twist the cliche into something interesting and even admirable, in the same obnoxious way as the protagonist. 
 There's even a mythical Gary Stu-like boyfriend figure that in a breathless YA/romance writer's hands would turn super stalker-creepy and clingy and more or less be an inconsistent mess. Instead, he ends up insisting on decisions that I'm frankly not used to seeing in a YA romance, and which I find terribly refreshing. Perhaps the only disappointment I had was in the lack of growth with the secondary love interest; he was introduced with great promise and humor, but quickly piffled away and was written off before he really got a chance. 
 Also, since I am well past YA age, I had to keep reminding myself that these are young and dramatic teenyboppers, and not to be too hard on them. Some of those rules that the main character likes to go on about had me rolling my eyes hard. And her friends just back her up on them, no matter how unreasonable. But if you stick with the story, it will sort itself out.