Pros
You get a good workout, only work about 4 hours a day depending on what part of the operation. The people you meet are great. I've known some people for the entire 11 years I've been there. Pays pretty decently well and I get a 401k and cheap health insurance.
Kontras
Hard on your body, you'll lift very heavy, awkward items. You'll get wrist pain, pain in your elbow joints from time to time. Being an Ops Supervisor there in a hub is horrible. You get yelled at over the radio all day and have to maintain crappy equipment that they never want to replace. As a package handler, it's much better but you'll have differing start times which I've always hated. We start at 4 AM but then all of a sudden we'll start at 2 or 2:30 some days which just makes it hard for me to maintain a consistent sleep schedule. Also on those days we work 5 or 6 hours straight without a break because breaks are not required by law in Utah unless you are a minor.