Has anyone traveled using megabus.com (Coach USA) bus line?

If you have any feedback please let me know, my sisters are traveling from Chicago to Cincinnati next month, th tickets are very cheap compare to Greyhound and that make us a little eskeptical about this bus line.
I am actually talking about the service in the US. but thanks anyways.

I used megabus (UK) to travel from Inverness to Edinburgh. It was very convenient. My ticket was actually text message sent by megabus. If I would have signed up a week or more prior to departure, it would have cost only a pound. I paid 5 pounds, which is still a deal for over 300 miles of travel.