I've worked for Subway, Taco Bell, and Sonic. The money and experiance are about the only two proes I see in fast food. One could stack the cons. Forgive me. Slow is good to start in, unless it's running out of business entirely. If it's 10am to 1pm with very few customers, then their store isn't getting alot of money. You don't live in a small town do you? If they have been advertising "now hireing" for weeks to years, there is something wrong with the employee enviroment.
Usualy in fast food things are done in haste, so some materials will still have liquids that haven't dried yet when your coworker pulls it away for use. People think the drive through is always faster than going inside. It's not always faster just because people use cars. Some customer will come along eventualy to hold up the line long enough for some ignorant person to then and later hold up the line by groaning at you. Not like it's your fault, but they'll blame you anyway just to feel better.
Some trucks will drown out the driver's voice, and you will have to ask them to turn off their vehicle. If they get mad, well too bad for them. Some coworker will be a doche bag to. I've dealt with a couple of people that were worse and more frustrating then my worst customers. Occasionaly, the sprite or myst flavoreing box goes empty, and nobody checks it. Thus, they give their customer a cup of carbinated water without knowing it. Lastly, something will always be unfinished.
I hope I helped sumarize what's to be expected in a typical fast food.