A couple years ago we purchased a used car from Holz. It was a good experience. The sales person was helpful and knowledgeable. He wanted to sell the car but also make sure it was the right car for us.
I used Holz service department once. That was not a very good experience. My car was still under warranty, but I had not purchased it from Holz. Holz was not willing to work with my warranty. I had to call GM, GM then took care of the situation. Holz was not happy about doing warranty work. I have not been back their for service.