Well I made it all the way through. It was hard for me to stop actually. I was intrigued by the story, by the idea. There was, as Ariel mentioned, a lot of sex. It is part of the story. (A friend assured me the movie is much cleaner.) But the sex was pretty quick, a paragraph or two, and easy enough to skip over for me. Oh, and the author, at first I thought she was British due to her choice of words in describing anatomy and such. Kind of awkward. I think she's a wannabe Brit.
Of course I do not believe in time travel, but it is fun to read about and fun to imagine. And I like the "high standards" of the time traveler - that he doesn't use time travel to his advantage really. (You know like, how superman makes the earth turn backwards to alter/change/prevent events and save Lois - nothing like that in this book.)
Ariel is right. You need a high tolerance for the sex or you can skip over the paragraphs as I did. I liked the story. It is a clever idea - uncontrollably jumping through time. But even with the spontaneity of his time travel, Henry manages to keep his time travel secret from many people close to him, he stays out of jail, he gets to visit himself, and he picks up a couple skills along the way to assist in his survival.