I don't think women can be good GMs. I know that some of you may think you had a good experience, but you were probably just looking at her womanliness. Really, the extra little bit on that last chromosome pretty much inhibits any kind of dungeon-planning ability, and then, instead of the DM Gland that produces DMatonin, she's got ovaries. I mean, c'mon, what kind of DM can you be without DMatonin flooding your system? Ovaries, man. Ovaries and an extra thingie on her last chromosome. I just don't see how anyone can be a good DM without DMatonin and with all that other weird stuff.
(Trolling aside: While I have never gamed with a female GM, that's more due to my lack of networking than to anything else. I see no reason to believe there's that big a deal, and little reason to believe that female GMs are going to be meaner, nicer, more into roleplaying, more into killing stuff, smarter, dumber, or anything else than a male GM with the same level of experience, planning, and personal maturity.)