I have to agree with Edgar that Humbert is, indeed an asshole. I think that because it is written, or rather the way Humbert describes everything, the reader tends to not really be so much disgusted with Humbert, but rather he invokes interest. As Krzys said in lecture on Thursday, Humbert is writing down his life and thinking about his actions right before he is about to die so his writing uses luminous language that compels sympathy. The reader does feel bad for Humbert and sees him as the protagonist even though he rapes little girls. The reader feels this way because, as Edgar said, he is telling the story so he is free to manipulate is, and he is also manipulating the reader with his fancy prose style that draws you in.
I too didn't think of Humbert and Lo's first night together as rape untill Lolita mentions it herself. I even had to go back and read that part in the book to make sure what I thought happened even happened. The way Humbert tells it, he says that Lolita kind of initiates sex, even though Humbert so longs for it, but this too could also be a manipulation. But I think if Lo did initiate sex, it does add to her whole mischievous characterization as she was plotting to leaving Humbert ever since that night. What Humbert does is wrong, and also that he kept repeating his offenses and would give Lolita gifts, money, and freedom to do so is wrong.
Yes, his prose style is fancy, but ultimately after you read the book and you think about Humbert you tend not to like him. He is a pedifile, rapist who descibes women who arent 12 year old nyphlets as "old, fat cows." Humbert... not so much a great guy.