Anyone reading this should first be aware that it is not a novel like the L. Frank Baum Oz books; rather it is a novelisation of the Disney film Return to Oz.
I am undecided whether I think this is a good book or not, because it's hard to tell what demographic it was intended for. I vaguely remember being terrified by the movie as a small child, and it is not something that I would want my kids to watch when they are under the age of five or six (I don't currently have kids; I'm just thinking of the future) as I found some of the scenes very disturbing. However, the book as it is written is really only suitable for very young children: the writing is very basic and unlikely to appeal to older kids unless they were huge fans of the movie and are reading it for that reason.
The best thing about the book, IMO, is the photographs. They are still shots from the movie, and they are quite lovely, and surprisingly clear for a book that was published in 1985. I particularly like the pictures of Ozma, who is as beautiful as I remember.
I do find that the book is let down by the writing. It's always going to be very difficult to compress a film of a few hours into a short book, but this (only partially successful) compression has resulted in several places where sentences seemed like total non sequiturs, and I had to backtrack to see if my eyes had somehow skipped past an explanation of how we got from sentence A to sentence B. I was reading this book to myself, but I imagine that if I were reading it out loud to children older than about 3 or 4, they would likely pick up on this.
Due to this, as well as the fact that some of the scarier parts of the movie have been excluded or glossed over (like Princess Mombi's collection of heads, or the fact that the doctor at the mental clinic died in the storm), I am assuming that this was intended for very young children, and as such it is quite charming, but older kids or adults who are expecting the sparkle of Baum's novels may be disappointed.