I rent here at least once a month for trips to CA for work. Being a member of their frequent renters club makes things really nice.
The speed at which you go from the bus / drop off to the car is amazingly fast. They don't have the nice cars like Hertz but I always seem to find something I enjoy for the long drives.
A couple of times I needed a van and their wasn't one in my section. The customer service rep got what I needed and got me on my way fast.
One thing I have noticed that is a negative is the National greeter who always welcomes you is not helpful. If you have an issue go to the customer service booth where the cars are. They have told me more than once that the greeter should have helped me. That's my only issue but overall a pretty good National location.