This weekend, the New York Times book review had a couple of letters in response to a previous review of John Scalzi's novels which commented on one of science fiction's most perennially controversial novels, Starship Troopers by Robert Heinlein. One of them is by John J. Pierce, who points out the long history of contention over the book and how Heinlein liked Joe Haldeman's The Forever War despite the latter being a direct critique of his book. It's an example of how irreverent and open debate is encouraged in the genre; as Gregory Benford put it, while in "serious fiction ... proceeds from canonical classics that supposedly stand outside of time, deserving awe, great and intact by themselves", science fiction books constitute "immense discussions, with ideas developed, traded varied; players ring changes on each other — a steppin'-out jazz band, not a solo concert in a plush auditorium."
Pierce is recognized among science fiction fandom as a critic, editor, and fan. He edited and wrote introductions for a number of excellent entries in del Rey's 1970s series of collections of the selected short stories by classic authors: The Best of Raymond Z. Gallun (the only volume of short stories ever assembled of one of the unsung early masters of the genre), The Best of Murray Leinster, and The Best of Cordwainer Smith (later followed by a larger complete collection of the author's short stories). He's also written four critical books on the history of science fiction (which I haven't read, but look intriguing): Foundations of Science Fiction (1987), Great Themes of Science Fiction (1987), When World Views Collide (1989), and Odd Genre (1994). I've also seen him at Lunacon in 2003 and 2005 on panels discussing topics such as favorite pre-20th century and out-of-print science fiction, and the New Jersey Humanlight celebration in 2004.