Worked at one for maybe a year and some change. Thinking back on it, it was kinda enjoyable. I liked my colleagues, I liked prepping drinks and getting orders out the window. I even liked mopping. The real drawback, what eventually drove me away from it, was doing it every day for the foreseeable future.
If I could, I would sign on to work, like, two weeks. Then move on to something else. Maybe pick up another two weeks when I felt like it. The idea that you have one job that you sign on and do everyday until you quit or die seems... silly. Surely it's possible to make employment more flexible -- to let people train for and try a lot of different things. How are you supposed to know what you like doing before you've done it? And, one imagines, a workforce with a better understanding of a variety of different jobs would be better equipped to anticipate problems and find solutions.
Fast food actually isn't that bad. I honestly think most retail/service jobs would be a lot more palatable under communism because there wouldn't be the constant push to cut labor costs. If McDonalds actually had all the employees it should rather than making one person do three people's jobs, it would be both easier for the workers and better for service overall. I could handle that.