Cons: We were unable to rent the car. The employee was so rude! I reserved the car through Kayak but the Avis directions didn't specify that we needed an alternate credit card, where to find the rental center, etc.
Cons: I made a reservation, called to confirm that the car was there (they said yes), but when I got there I waited behind a long line of people and was then told there were no cars available. Very frustrating.