Everything about this book is entertaining. I don't think I've ever been as entertained in my entire life. I carried this book around with me everywhere and probably embarrassed myself reading it in public places, but it's the kind of book that you never want to stop reading. The Gone-Away World has a refreshing sense of its own absurdity (because you don't spend a ridiculous amount of page space talking about an afterlife full of nymhpic, bouncing sheperdesses unless you are prepared to admit that what you are writing is not exactly Serious Literature), but it still has a solid, exhilarating plot behind it.
The best thing about this book is exploding sheep Ronnie Cheung that you can really feel Nick Harkaway's sheer delight in writing this story. Some have said it to be excessive -- he's a bit too in love with it, taking far too many tangential liberties, etc., but I think that's part of its charm. This book isn't for everyone -- you have to be with it till the end to really appreciate it.
(And what an end!)