I've taken Amtrak for shorter trips Downstate, never cross-country or anything though. It's pretty comfortable. I do wish there were later trains leaving Chicago. Except for one time when the train was delayed a couple hours due to weather (and this was the first time I was meeting my then-boyfriend's parents, they were picking me up at the station and my train was THREE HOURS LATE!

Oh yeah, and this was before we all had cell phones so they basically had to sit there!) I have not had any problems.