Clive Barker is a man of extraordinary imagination and, while HellRaiser is what people most know him for, I think his "young adult" books are what define him. And by this I don't mean sweaty teenager sex, but wonderful fantasy worlds that also have a tang of darkness and stories that have a conclusion beyond the idiotic morality taught to little children. They are also a bit more actual, without dwelling on feudal or anachronistic features like, say, Harry Potter or Lord of the Rings. I liked "The Thief of Always" and I also enjoy, although not to the same extent, "Abarat".
Abarat is a magical series, much like a darker Alice in Wonderland, with two books currently having been released. The classic "girl enters magical world" is expanded to the point of bursting with the description of the 25 isles of Abarat, one for each hour (including the 25th), each with their own features and crazy-weird inhabitants. Abarat is also a twisted mirror of Earth, with coca-farma conglomerates trying to destroy the magic in the world.
You can find a site at www.thebooksofabarat.com, very nicely done, that teases the imagination with flash animations and excerpts from the books.
I've read a review that compared Abarat to Harry Potter and even declared that it is the writer's alternative to it. I dare say that is completely wrong. The worlds of Clive Barker are about finding your way through your own inner power and imagination, whether you choose the path of Light or of Darkness. Purpose is what defines a Barker hero, not taking sides.
Bottom line, a nice book, clearly well written (I like Barker's style), and the storyline is detailed and well thought of. I may not be in a wonderland mood right now, but it is the best book I've read in the last month. There was an attempt to create a movie based on Abarat schedulled for 2005, but, according to the Wikipedia entry for Abarat, creative differences killed the project.