Yea, a couple of years ago I wouldn't have given a plugged nickel for their stock.
I haven't used Carvana myself, but I have two stories about them. First, my brother bought a vehicle from them about 3-4 years ago. That surprised me, as he is pretty much old school. He said the experience was fantastic.

Next, my local hardware store owner (he owns a small Ace Hardware store with three employees, including himself), purchased a 4WD Chevy truck for store deliveries. They would only deliver it to a location about an hour away. He took his mechanic buddy along to pick it up and immediately his buddy said that the "transmission wasn't right". After reporting it immediately, Carvana told him to drive it home. As soon as he got it home, he decided the transmission was on the verge of failure. He called Carvana back and expressed the problems and he wanted his money back. They told him to drive the truck back to the previous location and the sale would be voided. When the truck pulled into the original location, the transmission would no longer move the truck and failed completely. The store owner did get his money back after a week. He said the humorous part of all this was Carvana relisted the truck on their website and said that the truck has a "newly rebuilt transmission", all before the truck was picked up to be towed away.