I've bee using it for quite a couple of years now. They have a hefty selection of games to choose from, but you have to wait longer for the new releases since everyone is putting them on their queue.
I live in Philadelphia, Pennsylvania and they have an office in Pittsburgh, so when I request a game, it gets to my house in 3-4, sometimes 5 days. You can also buy games for a very good price since they are used.
What's awesome about it is that if there is an older, obscure game you like that you can't find at Gamestop or a rental store, Gamefly might just have it and you can keep it as long as you want.
What sucks is when things get lost in the mail/delayed and things get delayed. I ordered Ace Combat 6 back in JULY, and I had them resend it to me twice and still have not gotten it, to the point they won't send anymore without disabling my account. But it's a rare occurrence.
It's also an awesome alternative to buying. I am busy, I need more than a week worth of rental to play a game. I rented Super Mario Galaxy for about a month and finally got around to beating it. So I got what I wanted out of a game on my own time without paying for it.
