I'm not sure why they have such a low rating because I've never had an issue with either Dollar or Thrifty. I can only imagine a poor review is from someone who made their own problems.
I usually book through a third party website (such as Kayak or Priceline) and the desk staff has always been friendly and helpful, even though they're almost always busy at this location. This visit, I had a great price for a mid-sized SUV and they were able to bring my reservation right up and in the garage I had a few cars to choose from. Every staff person I interacted with was very nice and helpful. I have never gotten hidden or surprise charges. Why pay more when the service here is so good?