I took Greyhound for my trip and I have to say it really wasn't that bad. The ride was somehwat comfortable but my biggest beef is that they can't keep a schedule to save their lives. That & the on-board toilet was absolutly horrific. I felt really bad for those poor souls that had to sit back by it. The smell was awful. I ended up holding it for 200 miles.
In the end, you get what you pay for. I can't say that I would never again use the services of Greyhound but it certainly would be my last resort.