Pros
I believe the best thing about McDonald's is that it is perfect for young adults or students starting to enter the working world and looking to become independent. They are very understanding of school schedules and activities. They also are pretty understanding of time off as long as you ask two weeks in advanced. As for actually working there, its really not that bad. Its like most other jobs for new and unskilled workers or anyone entering the workforce, if you can suck in your pride until you find something better, it should not be too much of a problem.
Cons
The worst thing about working at a McDonald's is "Working at McDonald's". It is one of the lowest jobs a person can have in american society and many of the people that go in there don't have much respect for employees. You learn to deal with people and how to provide service with a smile no matter how much they may not deserve it. The next worst thing is that every day is the same. Same people, same work, and same problems. Some people can deal with that, but it can get old and drive you crazy in no time.