The Megabus is an experience! But for an inexpensive ticket it's definitely worth it!
If you are the first group they pick up you have your choice of seats, I recommend the ones downstairs with the table. Since they offer WiFi and an outlet for each seat you can get a lot of work done or play a lot of games during your trip.
The leg room is great and they make a stop at a really nice gas station/rest stop with a McDonald's attached.
Overall for the money its a great deal.