Way fun. I love books about books and book lovers. I love to get my geek on. I work with several people who have nothing to do with Google but regard it as the tech holy land, and it was fun to read about a book lover who is also in the Google acolyte crowd. Throw a little adventure, mystery and intrigue in, and I was hooked. [We'll just overlook the somewhat weak plot resolution at the end -- I didn't really care at that point.]
But the best thing about this book was the characters. I would love to hang out with them. They were all solid, intelligent people with an enthusiasm for life (with the exception of the necessary villain, of course). The book just made me... happy. Nothing terribly complicated about that.