The only time that I went to one, the experience was actually surprisingly good, but in my case, it wasn't a psychiatric hospital per se. It was an ordinary hospital with a section of it that was used as a psychiatric unit. I ended up staying there because I admitted to a counselor that worked in the ER that I was having thoughts about going postal at work and having a hard time controlling my anger. I didn't have a plan to act on those thoughts, but they were at least concerned that I might, so in this rare case, I felt like being kept there was a good idea, because the suicidal ideation was only half of the problem.
I only met a couple of people there that could be considered "crazy", but most of them seemed pretty normal. I don't really know why they were all there, but a lot of them felt like they didn't belong so I was probably the odd one out in that regard. As for the two "crazy" ones, they kept things somewhat interesting and they were both locked up in the isolation room at least once because they became violent.
Of those two, one of them seemed like she was extremely hyper all the time. She couldn't ever sit still and she was always bouncing around and giggling randomly, so I don't know what her issues were. The other one had a habit of getting worked up over seemingly minor things and he would punch the walls so hard that he drew blood from his own fist, right before he started running around and screaming at the top of his lungs. He did that twice while I was there.
Aside from those few instances of craziness, the rest of the time that I was there involved group therapy sessions and watching movies most of the day. Night time was kind of boring because I didn't sleep very good and there was nothing to do since all of the entertainment areas were locked until the 1st shift staff arrived. Even though it wasn't always a fun place to be, it certainly could have been a lot worse. There is an actual psychiatric hospital nearby, at a different location, and one of the other people that was in the unit told me she had been there before. From the way that she described her experience there, it made it seem like the unit I was staying in was a 5 star hotel in comparison, so I would say I got very lucky that I didn't go to the other place.
When I finally got out, I actually felt hopeful that things were going to get better, until I got the medical bill. That was when things started to go downhill again and I ended up becoming far more suicidal than when I was hospitalized. The debt was only a minor thing compared to all of the other problems I had, but it certainly didn't make things easier, that's for sure.