Pros: pays for school, good way to stay in shape, wonderful supervisors and managers, wonderful co-workers that you can chat with as you work, numerous discounts at popular stores, plenty of opportunities to advance, thorough and explicit training
Cons: the trailers can be really hot during the summer and really cold during winter, workload is difficult to get used to, lots of rules to learn
Although I briefly worked at UPS, I did enjoy my time there. I started out as a Package Handler and loaded an average of 300 packages an hour onto various trailers heading to various destinations. My supervisor was a glorified disco-loving water boy (I mean that in an affectionate way) who just loved to make you smile and motivate you, and it was overall a very positive environment and I enjoyed working here. They help you pay for school, so that's a nice plus, as well as offer lots of employee discounts to many popular store chains, such as Barnes and Noble and Apple.
The hardest part of the job was getting used to the workload; it is basically like going to the gym for six hours, but it's fun, and it's like playing a giant, 3D version of tetris and has you constantly thinking about where you put the next package. Safety, rules, and regulations are numerous and difficult to learn, but they go over it with you every single day for a month until you can recite it from memory.