The Ascendance of Firefly, a good review of the show from a relative newcomer, discussing what really makes the show work.
To me, Firefly is primarily an example of what happens when a talented group of people come together and give their best to a project which is itself led by someone talented giving his best.
Nothing shocking or new for old-times to the Whedon-verse, but well-written and focused on drawing in new fans regardless. Might be a good article to point doubting new-comers toward (if you don’t have time to force-feed them an episode of the show itself, which is usually all it takes).
The story itself is engaging, and doesn’t allow the futuristic backdrop to rob it of a plausible storyline. It is not a prerequisite to have enjoyed Sci-Fi previously — this isn’t traditional Sci-Fi.