I enjoyed both of Tim's books. Yes, his methods are a bit... unconventional, but the underlying principles are good:
Book 1: "Do less..."
Book 2: "...and measure it."
Book 1 (4 Hour Work Week) is especially interesting in contrast to other productivity books; books like GTD are about cramming more into your day. 4HWW is about identifying the highest impact things and cutting out the rest.