The first thing I noticed about train travel is a comparative lack of security. There were no guards at the doors, my bags were never searched and no one ever asked me for ID. If you had a valid ticket, you were good to go. In fact, they didn't have any problem with non-passengers waiting in the lounge or coming out to the train with you.
Part of this reflects good sense. What are you going to do with the train now, Mr. Terrorist? Move it back and forth after the passengers have jumped out the windows and doors? The other part is that they intentionally cultivate a "family atmosphere", in fact, the train to Dallas was 45 minutes late while they kicked off some kids for smoking weed. Cause trouble, and they stop the train. I took sensible precautions, but I never worried about leaving my stuff unattended at any time.
The bad about this casualness is that it's very confusing at times to figure out what is going on. Sometimes they scan your ticket at the door, sometimes in your room, and sometimes in the lounge. Train 20 to Chicago won't necessarily have a big "20" on the nose. Like any other mode of mass transport, the speakers don't work very well; of course I was next to the lady (my grandmother did the exact same thing) who was loudly reading the ingredients off of a Chicken McNugget sauce packet while I was straining to hear which door I was supposed to assemble at. I just acted like one of those cleaning robots that trundles along until it hits a wall: Asked the first Amtrak employee I saw which way to go and went that way until I saw another Amtrak employee. I repeated the process until I was firmly in my seat.