Always an early adopter, I'm taking one of the inaugural Virgin America flights from SF to LA. Since thy are also in DC' (and I'm bored), I thought I'd provide a review.
At SFO, they are located in the International Terminal, which is rarely busy, has good food, and is nice and clean. This is a huge bonus over Southwest at OAK, especially at the same price. Waiting for the flight, I can see that mostly young people are early adopters (or fans of Virgin) as there might be 5 people over 40 at most waiting for the flight.
The staff at checkin were extra friendly - same as Virgin to Europe, which is encouraging. Though my flight is only an hour, I'm most excited to try the 110V outlet at every seat (for the nontechies, thats just like a plug in your wall). This will come in very handy on an SFO-DC flight. They also claim video on demand, over 3000 mp3s, and a cashless plane where you order from your seat tied to credit card you used to purchase your flight (brilliant).
The stewardesses just arrived and I'm a little disappointed that they're not as hot as the ones that fly to Europe, but they're not ugly. Nor do they have a funny accent.
One interesting thing: when picking my seat, I noticed that the emergency exit was available. When I clicked on it, it said I could have the seat (and the extra leg room) for $15 extra. I passed, but when I arrived at the airport, I asked the lady about it and she said that someone has to sit in that seat so she gave it to me free. Keep that one in the back of your mind. In addition, the first class seat is only $40 more the highest priced ticket ($120 vs. $160 one way) at least to LA. Two weeks advance purchase is $44 for coach and $149 first class.
We're boarding now so I'll provide more after (or during if that's available) the flight.