It's interesting that the two Baum books that I own are The Wonderful Wizard of Oz, which is the first Oz book, and this one, which is one of the last.
Many characters that I never heard of (the Tin Solder, Tick Tock, The Glass Cat, The Pink Kitten, Trot, The Wooden Saw Horse and more) were introduced in the books in between and all make an appearance here. This isn't a real issue but is a little like when they have all the Dr. Who's in a special episode. It tends to clutter up the action.
Overall the story and the methods the heroes use to overcome their obstacles and enemies are creative and fun. The birthday party in last chapter is the exception and can easily be skimmed over.
Frank Baum's writing is interesting in that can be alternately be very good and rather mediocre. It feels that once he wrote something once, he never went back to tighten it up. He could very insightful about human nature and also totally naive or at very least simplistic.
Overall I quite liked it.
My two Oz books will be set free, going to my sister for my niece and nephew.