Cons: Everything. They did not have cars available and clerk was extremely unhelpful and rude once he saw where I booked the car and the Kayak rate. Ended up renting from Hertz a couple booths down the hall. They were much better.
Pros: Moved my fiancé from Iowa to Boston. We got a brand-new Dodge Caravan with fold-flat seats, SiriusXM radio, and the flex-fuel capability which was a major money-saver. Was as smooth as you'd expect of a car under 15k miles.
Cons: The van had a lot of someone else's trash inside when I picked it up. I spent a half-hour cleaning it out after picking it up. There were chip bags, pop bottles, grease streaks, and a persistient stickiness to the steering wheel that required dish soap to remove. I suppose this is the price paid for a low rate.