If it's like here in Minneapolis, it depends a lot on the route. The express bus I take from the suburbs to my job in downtown is really nice - big coach bus with reclining seats, wifi, and plug ins. Contrast that with some of the inner city routes I have to take sometimes and it's like night and day. I used to work 3rd shift and some of the shit I saw while taking a bus home at 3 AM were unreal. Like a guy who got on with a bad full of meat from a grocery store and just sat for a few miles poking holes in the packages and drinking the "blood".
The train we have from downtown to the airport/Mall of America/suburbs is generally ok but I've seen some sketchy stuff on there as well. Since technically you don't have to pay a fare to get on, it's kind of a haven for homeless people. Most of them are ok, they're just sleeping or whatever. But then you get the dumbasses pissing on themselves, smoking, harassing people for change, etc. I've had to step up a few times when some drunk was groping young school kids.