I read "Three Men in a Boat" back in grad school -- nothing to do with grad school, but I could check it out from the Harvard library -- when it was referenced as a source for some contemporary SFF (Connie Willis, I think; I never actually got around to reading the book) and highly praised. It was a hoot. I think I also picked up "Three Men on a Brummel" but I don't remember much of it.

"Three Men In A Boat" is by far his funniest. He wrote two more in the same vein, but they weren't as successful. Jerome's essays, though, amuse me very much.