I work on an adult inpatient psych unit currently (1 year), worked at an child/adolescent psych hospital (1 year) and worked adult med-surg (3 years)
Psych nursing can be so boring!! You don't spend much time with the patients. The milieu therapists who are out in the unit with them spend their entire shift with them. It's true that we give meds and chart mostly. Yes, you assess but it is not what is drilled into our heads in school and what is experienced on med-surg.
I tell all new grads to work med-surg first then go and do whatever. I didn't like med-surg that much in clinicals and didn't really like it while I was doing it as a job as it is so brutal- 95% harder than my psych job. I knew that it would look good on my resume and I really wanted to use the skills I learned! Med-surg is what nursing programs focus on and where all of our skill labs skills are used constantly- NG's, Foleys, IVs,trachs, feeding tubes, chest tubes etc.
There are now nursing programs that don't even have psych clinicals, the content is taught and SNs are tested but I guess that clinical time goes to something having to do with med-surg.