This was a really pathetic book - a sad departure Levine's other fantastic novels. The idea was interesting (a take on the story of "Snow White" where her desirable trait isn't beauty, but instead is her singing voice), but the execution was horrible.
The book staggered under one major inconsistency: the main character is horribly ugly, but the prince falls in love with her very quickly anyway. Hopelessly romantic? Perhaps. But I call it an inconsistency because Aza was not only unlovely, but almost unlovable. Many wonderful heroines are not particularly beautiful (Jane Eyre, Jo March, Anne Shirley, Princess Amy, etc.), but they have wit, strength, courage, charm, or passion that makes them remarkable. Aza had none of these - she was whiny, miserable, thoughtless, and full of self-loathing throughout the entire book.
Also, the prince likes her almost immediately, before he has any chance to get to know her: this would suggest to me that either the prince has horrible taste in looks, or that Aza really isn't as ugly as she constantly tells us she is (which would only make her whining all the more exasperating). Her amazing voice and ability to compose music are impressive to him I suppose, and her "ability to make him laugh" was apparently important...but he lives in Ayortha, where almost everyone sings and composes well, and he was called "merry," "smiling," and "laughing" long before Aza captured his heart. Even knowing that she deceived him, he falls for the ugly wet blanket. She was never clever, except in her skill at singing. She didn't do anything smart, and certainly didn't act brave. Her sister says she is kind, but we never see her acting like it. What on earth is there to like about her? Her characterization, in my opinion, ruined the entire book.
There were other problems as well: Couldn't Levine have come up with a more realistic antagonist than...Lucinda? Of course everyone who read "Ella Enchanted" dislikes her already - it was so much easier to use her, than to actually design a characterization for someone who would hand out such a dangerous gift at weddings. Unfortunately, it didn't fit her character at all (Lucinda loves attention and admiration - she would never visit the bride alone and give the gifts with absolutely no ceremony or a huge crowd of people around; and why would she give a potion of disguise to someone she was making beautiful?), and it even discredits her change of heart that comes at the end of "Ella." It was a total cop-out.
Last of all, it was predictable. Not just in the way that all fairy tales are rather predictable, but in the way that makes the book really boring because the main character is being such a blind fool, predictable. Besides the fact that it was clean, there is nothing in this book to recommend.