Is Nabokov's masterpiece still shocking? (Short answer: YES.)
Lolita turns 50 this year, and having stayed so perverse, it remains fresh as ever. To fully appreciate its perversity, though, one must first appreciate that it is not obscene. Your run-of-the-mill obscene masterwork—Tropic of Cancer, say—demands that you, enlightened reader, work your way past the sex and excrement to recognize how beautiful it is. But with Lolita, you must work past its beauty to recognize how shocking it is. And for all its beauty, for all its immense ingenuity and humor, one easily forgets how shocking Lolita is.
I think that's really the genius of the book: wrapping such disgusting subject matter in some of the finest literature ever produced. I suspect that may have been the challenge Nabokov set for himself, too, and somehow he pulled it off.