Just how a good children's book should be. Well-written with good characters and interesting illustrations - so much to go looking for in the pictures!
However, to talk only about the hidden characters would be to diminish the impact of the simple but well-developed story - the apparent sadness of Albert and the comical attempts of the other toys to cheer him up.
Lots here about acceptance and not judging a book by its cover (although this book is great inside and out!), and well-loved by my 3 year old daughter - even if she doesn't know who the Trumpton fire brigade are!