I love Babette Cole. My children were practically brought up on her picture books, and Mummy Laid an Egg is surely a shoo in for classic children's picture book of the century? I was interested to see her move into transitional or chapter books and delighted that I might be able to offer books by one of my favourite children's authors to the children at school.
These transitional books are shorter than an average novel, and still have elements of the picture book about them, making them easier for children who have just moved away from picture books to get to grips with. The market in these kinds of books is currently booming, which is a good thing.
Sadly, I did not think this book was a good thing. The third in a series, it is virtually impossible to read as a standalone book. There are too many unexplained threads, characters and back stories to make it intelligible if it's the first one you pick up. The language is quite complex in parts, unless you are totally obsessed by horses and actually ride and look after real horses, as some of the language gets quite technical and there are lots of horse related in jokes and themes, including chapters which explain how to play polo. I can't see that being terribly successful as a topic to interest young readers, certainly not in the school I work in. I think it is a little elitist.
The whole magical universe peopled by talking unicorns theme didn't really work for me either, and I didn't totally understand how that worked, because that was obviously explained in books one and two, which I hadn't read.
So, to summarise, only suitable if you're going to read all the books in order, you like magical ponies, and you like and know enough about real ponies for this to be enjoyable.