Pros
Autonomy. Tuition Reimbursement. Good wage for unskilled labor (great for students) Paid to exercise. Neat logo/uniforms/design. Reputable. I worked the PM sort alone at a small station through college--scanning and loading an average of about 750 packages in a 2.5 hour period. You're graded for accuracy each night by comparing your (outbound) scans to the pick up scans done by the CSAs and Couriers--I believe 99.4% was the minimum goal--which means out of 750 packages and documents, you could only miss four to meet goal. At my station, they don't randomly drug test handlers (unless you operate FedEx vehicles, or there is some type of accident). Advancing isn't that difficult if you're a competent, hard worker--although FedEx is vehemently anti-union so if you like the idea of being a courier and committing to a company, UPS will pay more in the long run. Express shipping is extremely expensive, so you're not unloading oddly shaped 140lbs packages all day (although it happens).
Cons
In the smaller stations, the amount of work required of you can border on insane. Stressful environment. They seem to go through low-level managers pretty quickly. Can be odd hours (Ramp workers have shifts at 3am, drivers are usually in the door at 6am).