We utilize the drive thru a lot because we kind of figure SURELY they will improve at some point, right? If you check your order before driving away, you should be fine. Not checking my order before pulling away has bit me in the bootie a few times. (We made it home one night and literally half of our large order was missing) Now I am sure to check and it seems to work. I do find that they miss something out of the order more times than they don't and I would be a bit more impressed if they acknowledged it.
I went there at 11:45 this last Friday night and they were out of iced tea, Sprite, and Diet Coke. When I said "Really, you're out of all 3!?" the girl at the window was quite tart when she replied "Well, it IS the end of the day!". Um, don't think so.