In Barbara Ensor's retelling of Thumbelina, the author's conversational tone works better than it did in Cinderella. Perhaps this is because the book already features many diary entries, although another explanation is that I really didn't know the story of Thumbelina at all!
Apparently, Thumbelina is almost married off to a variety of animals until the end, when she meets a tiny king that falls for her. I don't think it is too much of a spoiler to state that Ensor gives the reader the traditional happy ending, but includes an alternate ending for the more independently-minded reader.
The silhouette illustrations and diary entries make this a quick read, although the fact that it is broken into chapters will make the developing reader feel more mature and accomplished. I suggest checking this book out of the library...it is such a fast read that your book money would be better spent on more substantial fare.