Overall, the company is just as incredible as everyone says it is. However,
I spent 3 months at Chick-fil-A and I've never been so stressed in my life. Having seen the back, I can confirm that the food is clean, professionally handled, and made with the highest care. The staff really do care about the customer, which was one of the things I loved about the job. However, just like with any fast food chain, each restaurant can be run differently depending on the management.
The management at the store I worked at was really not good. They pitted the front counter against the drive thru, they implemented a mentality of "every man for himself" during rushes (which, mind you, was pretty much all the time), and training was literally done in a single day. Lucky for me, I had experience with a register before then, but I have no idea how 15 year old kids can do that as a first job.
I would just say do a lot of research about which one you're looking to work at, because some can be much more busy and poorly managed.