Pros
Allows you to learn how to work in a fast paced environment and deal with difficult situations and even more difficult people. You can knock it, but these are important skills to learn in life. Most locations I've seen, especially the one I worked at, had a familial bond between employees which is something that empowers employees to deal with even the most difficult situations
Cons
I know it probably goes without saying, working in fast food and all, but some of the customers are downright cruel. Throughout my time there, I was screamed at, verbally abused, had coffee thrown at me, and was even threatened a few times by angry customers. However, this is generally more than made up for by nice customers who always brightened my day, often telling a joke. Even after I stopped working there, I sometimes saw regular customers around and they went out of their way to say hello to me. When I worked there, the starting hourly was ridiculously low (I think exactly minimum) with only the vague promise of a 5 cent raise every year