I had Gamefly for about six months. I honestly believe they have some sort of priority shipping depending on how long you've had the service. My first two months, the turn around was about 2 or 3 days. By the fourth month, it took them a week to get me another game. It wasn't like the fourth month was the middle of winter, either. It just got worse from there.
I just never saw the need. I'd rather play the demo on live, buy it and download it or purchase it at the store instead of waiting for the mail , just like I'd rather live stream Netflix instead of do the whole DVDs in the mail.
I never used Gamefly, and I don't think I ever will. I'd rather be on the good graces of a friend and borrow the game from them for free. If I had to pay to rent I'd rather use Redbox to get games rather than pay almost $30 every month for Gamefly. Also, with Gamefly don't you have to wait for the game to ship to you?