We returned from WDW Nov. 14. We rented for a week during our stay on-site at Caribbean Beach. We had a bad experience with National at Car Care Center 3 by Magic Kingdom. It took maybe 5 minutes to get their from our resort with their pick-up service. That was the good part. They had upgraded our car for us (which we didn't want) and didn't have one ready in the grade we had originally reserved for. The counter lady was extremely grumpy and rude. Our car was dirty inside with stains all over, plus liquid splattered all over the dash and doors. The car vibrated so badly my back began to ache horribly! We complained when we returned it and had the same grumpy and rude lady who didn't do anything except to tell us to sign at the x. We have since sent a letter to the company but haven't had a return reply from them. I would recommend renting from someplace else, personally. We will never rent from them again and would definitely go off-site to rent from another company.
I'm sure there are plenty who've had good experiences with National. We just didn't have one and neither did others who were renting the same time as us.
Good luck and have fun!!!
Cindy