Had a friend that rented with them once. Rates were good, car was clean, customer service was horrible.
If you use them make sure you have a credit card, a valid drivers license, and proof of insurance (so they can't make you take out their additional insurance). My friend didn't have the insurance policy when he rented the car and they were going to charge him an arm and a leg. A day later we drove back with a faxxed copy of his insurance from his company and they argued with him about it. It was a lesson learned, I just don't think we would have had the hassle at Alamo/National or another major chain...