Coworkers are pretty nice, but customers can be absolute turds sometimes.
Pros
They're pretty flexible with your hours once you've been there for a while so you can work casually and still juggle school and family and friends. I did have a manager at one point who would get really upset if you asked to switch shifts, i think its a bit hit and miss depending on where you work. Coworkers are friendly and welcoming and you can make some good friendships while you're there. Working with friends can be a lot more fun than working with strangers.
Cons
The pay is peanuts, but what can you expect from a job you need no qualifications for. It can be pretty stressful, especially during lunch and dinner rush when you have to get those orders out ASAP. About 20% of the customers think they're the centre of the universe and will treat you like the scum of the earth. You have to learn to brush it off and not let it get you down pretty early on or you'll hate your job.