For me, it ended up not being as bad as I thought it would be, mostly because of the instructor and friends in my clinical section. I was scared ******** the first time I went to a mental health hospital because it was an end-of-the-road type of place and the people there were really far gone. I nearly quit because I was so petrified and scared of the people.
Now, I understand that it was a vital part of my training, but I still wouldn't choose to work there! :P One of the things that helped me the most when we got to our main clinical site (which had small children up to adults) was taking my teachers' advice and not reading the charts before talking and interacting with the patients. I didn't understand why she said this until I read the charts at the end of the day....if I'd read the charts first, there was no way in hell I was going to try to get close to some of those people!! That, I think, is the most important thing to do. Just keep an open mind, get through the day, and who knows, you may even like it!
I had several friends who thought they'd hate it and ended up being mental health nurses!