Spirit of the Century is by a wide margin the best pulp game I've yet read, and yes, I do include the one I co-developed in that. Spirit builds with flair and intelligence on its predecessors, including Adventure, transmuting good intentions into brilliantly smooth execution. It is a beautiful little volume, well-written, entertainingly illustrated, and full of the fun. If you like to play pulp adventure roleplaying, then you want to check this out. Trust me on this: I repeatedly had the thought, "I wish I'd done it that way", "I wish I'd had that idea", and so on. It's great stuff. Go support Fred, Rob, and the gang.
(They generously threw in Don't Rest Your Head. My thoughts on that when I read it.)