Basically starting this thread to defend Catch 22, which is getting a bit of a battering in the Books that Disappointed Thread.
I did the reverse on Catch 22 by reading the book and then watching the film and I didn't like the film, the book is better

I did the reverse of that reverse with One Flew Over the Cuckoos nest but enjoyed both the film and the book.
I find a lot of books are being hyped to unbelievable levels nowadays so they can achieve massive figures right out of the gate. This process obviously leads to disappointments but what books have lived up to - or even surpassed the hype - for you?