I worked at Burger King in high school. I had decent bosses, and I never had major troubles, because I came to work on time, did my job, was generally a reliable person. Customers CAN be dicks, but not all of them.
The bad things? You smell like a giant burger at the end of your shift. After one good bus rush comes in, and you see the disgusting amount of food, you'll be turned off of burgers after a while. The uniform.
The good things? There are always a ton of high schoolers working there, so unless it's prom or something, you can usually get a night off if you need it. Plenty of available hours, even in the summer. Teaches responsibility, nice little paycheck, doesn't take much brain power, just organizational skills.