Mikkel book is easy to undesrtand and beutifully illustrated. It works like a cross between Evening and Scott approaches. Plus it is the only book about Lightroom 1.1 at the moment. Both Evening and Scott were done for LR 1.0 although a downloadable update for LR 1.1 is available.
I give Mikkel Aaland "Photoshop Lightroom Adventure"
If you are looking for a Lightroom book that it is easy to understand but has substance to it, you should consider Mikkel Aaland LR book.