Getting your hair cut at a beauty school always has it's pros and cons: it's cheap, but then again you're getting your hair done by someone who has only been cutting human hair for about two weeks.
Paul Mitchell The School generally does a really good job. They're heavily supervised and have to check off each step of the process with an instructor and tell them what they're going to do next. This is good, because it means that you have a whole group of professionals discussing your hair cut, and that let's you know in details what they're doing, and can stop them at any point if you don't like what's going on. The bad thing is that it generally takes a long time. A LONG time. I got my heair cut and dyed their once, and it took them four hours. If you're getting a basic trim, go for it. If you're feeling adventurous in the hair department and are willing to let them get creative on your time, definitely go for it.
If not, get your hair done somewhere else.