Your pretentious 'friend' will always turn his nose up and snort at you about how 'the book was so much better darling'. I don't think there's very many instances where that pretentious git is wrong, but there must be a few.
I can think of only one off the top of my head:
Fight Club. Awesome film, just about ok book.
Mayyyyyyybe also American Psycho, which pissed me off with all its 13 page Tina Turner insights or whatever. Film was ok, book was shitty.