I've flown on Song from Boston to Orlando. Not only was the price right ($120 round-trip), but the in screen TVs kept me entertained. You have a bunch of free channels (I watched American Chopper the whole way down), and they have music trivia you can play on the screens with fellow passengers, and you can actually watch the flights progress on maps on the tvs (which I think it REALLY cool). It was really entertaining! It was probably the most enjoyable flight I've ever been on, and it was cheap! I dont think it gets any better!
The food is overpriced, but I always bring my own stuff to eat, so I dont mind. I definitely agree with MKT.. fly them!