As awesome as Anne Hathaway and Julie Andrews are, the characters in Meg Cabot's novel are even more hilarious and entertaining. Mia is younger and more awkward, Grandmere is more ridiculous and overbearing, and the rest of the characters are more real and dynamic in a way that only Meg Cabot can pull off.
Pros: written in diary format, the protagonist Mia is extremely connectable and vulnerable, and has a lot of insightful things to say about being a young girl in high school. Set in the rich backdrop of New York City, Mia navigates the ordinary (gossip, boys, algebra, school dances, divorced parents) and the extraordinary (paparazzi, princess lessons, making the cover of the newspaper) in beautiful prose and hilarious asides.
Cons: not very many! It's possibly a little dated - technology makes much less of an impact on Mia's life than it would today.
Overall, I can't wait to read the next ones!