Can't speak about IAD, but I can speak about the jetBlue product (BUF to JFK in April):

Checkin in BUF was dedicated and very quick.

Seats were cramped - typical coach. Plenty of overhead space

The onboard direct TV was cool, we were joking about what would happen if, as we were watching CNN, they interrupted with a report of a jetblue plane in trouble over new york.

Service was friendly, the blue potato chips they served were great.

I'd definately do it again.