Service INSIDE can be slow sometimes, since they seem to worship the drive-thru customers and get all of their orders first, or at least with significant priority.  Staff is polite.  It's a real PITA to have to get refills from them though, instead of having the soda dispensers out for self-serve.  Are they really saving much money by doing this?  When there are lines of people to order, it's a bit much to butt in line to ask for a refill... or maybe that's the point.