I like artworks that you just think about. That just touch you, disturb you, give you pain, make you uncomfortablem, make you bother.
I saw "28 weeks later" yesterday with a friend. And like "28 days later" its not just a "Zombie"movie, its a deep and disturbing movie, that flows deep into the way things roll and things can roll.
This feeling of pain after seeing artworks shows you that you are not prepared for that what the artworks shows you, yet, and helps you getting there.