I am not overly fond of the word genre. Sometimes, of course, it is simply used to describe a type of book that makes use of certain conventions. However, for many people, the word has a pejorative taint — they see genre fiction as being somehow "less" than non-genre writing.
When these people find that they really like a particular work of genre fiction, they're inclined to use phrases like "transcends the genre." Though I am not a particularly violent person, hearing this always makes me want to throttle the speaker. Genre labeling not only ghettoizes particular books, but it narrows the world of literature for readers, rather than expanding it.
And speaking of genre, although I don't consider myself at all a science fiction/fantasy fanatic, I must say that selecting the books for this topic was harder than any of the others that I've done. There is simply so much excellent stuff out there — both new and old — that I know people would enjoy, that the list could have been at least four times as long. As it is, I know I've omitted some wonderful novels, like Ursula Le Guin's The Wizard of Earthsea, Dahlgren by Samuel Delany, George R.R. Martin's Song of Ice and Fire series, Robert Heinlein's novels for young teens, like Between Planets and Have Spacesuit, Will Travel, Clifford Simak's Way Station, Dan Simmons' Hyperion and sequels, and on and on and on.