I had heard about the Harry Potter books, and that they were really good, so I decided to wait until they were all written before I started reading any of them - which turned out to be a good plan I think. I cannot imagine having to wait a year after the climax of the Half-blood Prince. I read them all in one go shortly after Deathly Hallows was published. I think they generally got better and better, except I found Order of the Phoenix to be outstanding - lot of character development in it.
Anyway, I'm now re-reading them to spot clues and hints and to admire how they've been set-up in a certain way right from the start. Who remembered Sirius Black and his motorbike were mentioned in Philosopher's Stone when they read the books the first time?!
Am on Chamber of Secrets in my second reading, and hope to continue to enjoy the series for some time.