Pros
The pay is very decent. As a seasonal employee, I got almost a dollar raise every year. Almost every one of my supervisors was a pleasure to work for. Many of my coworkers were great to work with, if I'd take the time to actually get to know them. The hours were very steady, and overtime was often available when orders were up. Despite the areas management is lacking, if you aren't afraid to ask people around you questions and you aren't afraid to be be a little clueless the first time around on a job, you'll do just fine! The biggest reason why people hate their job or quit is because they got stressed out. Exhibit the desire to learn and work hard, and you'll be rewarded for it.
Cons
There were no benefits, and taking time off work was not often possible. You are frequently thrown around from job to job, presumably to be more useful for multiple positions in the "streamlined" work force. It can be stressful, because the training process is usually shrunk from one week to one hour, and you're left all alone to figure it out for yourself. Let's face it. There is no real training process!