No kidding. Firefly (and Battlestar Galactica, the new series) are both "best of breed." I'm honestly not sure how many times I've seen each episode of Firefly. I've seen each episode at least 8 or 10 times, probably more, and I've only had the DVD set for about 5 months now. And Serenity? Well, it shipped the Tuesday before Christmas (I ordered 1 for myself, and 1 as a gift for a friend), and it arrived on Thursday. I watched it Thursday night, again Friday night, and then Saturday (Christmas Eve) when I took it to my friends' house, we watched it yet again!
I've seen it at least four more times since Christmas.
And I've watched the BSG mini-series/season one DVDs multiple times as well.
Mark