I rented a Lamborghini Gallardo for four hours as a birthday present to myself. It was a splurge, but it was worth it. I did have one of the groupon deals as well. The car I got was a 2012 model and was extremely clean, it did not look like a tired rental car. The service guy that rented me the car was great and explained everything. The car uses a paddle shifter (no clutch) and it was pretty easy to use the paddles or it can also be used in full automatic mode.
The only negative item was we were told the light was on for the tire being low on air and we were told that the tires had just been aired up and the light would go out. It never went out for the 60 miles we used the car and every once in a while it would let out an annoying beep. I also rented on a Sunday and the rental office is not staffed at all times. I was supposed to turn my car in by 2pm and I got back there about ten minutes before that and there was not anyone there and I had to wait until 2pm for the guy to show up.
I would certainly rent from them again as the smile on my face after driving this car made up for the two minor inconveniences. I had considered renting from one of the other companies that does guided tours, this was much better as you have complete freedom as to where you go and you do not have to follow any other cars. I took the car up to red Rock Canyon and I would highly recommend this to others as you can test out the handling capabilities more away from the city.