Fantasy and fun in a superbly imagined multiverse, this is undoubtedly one of DWJ's best books, and deserving of its stars. This story is full of laughter and doesn't take itself or the whole realm of fantasy/scifi too seriously. Any science-fiction fans with a sense of humour will delight in her hilarious description of a convention!
The key characters are delightfully engaging and you will find yourself wanting to know more of their escapades. The good news is that a second book (not strictly a follow-on, but set in the same worlds) called "The Merlin Conspiracy" is also available.
The only criticism is that the ending feels a little drawn out and seems to ramble. However, this would only knock off half a star rating at most, and the rest of the book is well worth the reading. Although aimed at 'adults', there is nothing in this book unsuitable for children, and it will also be enjoyed by younger readers with a good grasp of the genre or familiar with her other fantasy books.
Recommended to many friends, all of whom loved it. One of my personal favourites!