This series of books, of which these are the first three, is entertaining and addictive. I found the character of Mia delightful in a neurotic-teenage-girl kind of way. (Please forgive my redundancy.) From the first I realized that my children were too young yet to enjoy this series - it is inappropriate for anyone pre-teen or younger - but after reading the entire series so far, I've decided that I don't want my children reading it even when they are older.
As the series progresses it deals with more and more serious issues in ways that I'm finding less and less responsible and moral. I can overlook the heavy-handed political bias but the moral prejudices worry me. The idea of virginity as anything worthy of saving is laughed at and the concept of waiting until marriage is considered ludicrous even by "silly," romantically deluded Mia. Worse, Mia's desire to keep sex as something special is shown as possibly destroying what is supposedly a healthy, potentially life-long, true-love relationship (even though at the point where she is considering having sex she is still under legal age).
For any parent who does NOT share the author's values, I would strongly recommend keeping your children and teens as far away from these books as possible. They are too engaging and enjoyable. With all the references to pop culture the world of these books feels like the "real" world, only lacking in any sort of common sense or traditional values as far as sexual and personal relationships are concerned. If you do not want your children confused by the supposedly "modern," hedonistic and self-centered attitudes these books take for granted as normal and proper, it is better not even to let them start reading the series. Once begun, it will be difficult to stop.