I typically book directly with a preferred company, but it was Thanksgiving weekend and prices were out of control. I checked Priceline and decided to give it a try. I used Priceline to book a car rental with National and found a great deal that was half the price I found with National directly. I had zero issues. After paying through Priceline and reading the fine print about No Changes/No Cancels/No Refunds, I checked my booking on the National site and all my info was there. When I arrived at my destination, check-in was fine. After returning the car a few days later, I got a receipt from National and an email from Priceline. All good!
I would use Priceline again.