Well, I got the chance to fly Skybus today between CMH and SWF.
Since I checked in online and didn't have any bags to check in, I headed straight through security to the Skybus gate area. It reminded me of a Greyhound bus station, albeit much nicer.
Then, I hopped on board the plane (I think it was N554SX... it was one of the A319s with dual overwing exits on each side). On board... it was cramped... I've never been on a more cramped flight (not even on regional jets!). Fortunately, there were only about 30 people on board the flight, so I had a whole row to myself, which made it quite a bit more comfortable than normal. The service was very friendly, and the flight was on-time.
I did buy the hot meal option (a pasta meal) and a Sierra Mist Free on board... it was $12 total, but it was quite good by airline food standards.
Would I fly Skybus again? For short to medium-distance domestic flights, yes. But not for long-range flights... the seating is too darn cramped.