I have it. I ignored it for years and then decided to try it this year. I have to say I am actually very much impressed. There are a handful of games I wouldn't buy even at a cheap price just because I'll play them once and then they will sit around so I got GameFly and have been able to do that. You just put the games you would like to play in your Game Q (List of games you want to play) and then they send you the one on the top of the list or if that one is not available then the next available one. I have never had a problem with not being able to get a game though. If you want to pay a little extra you can have more than one game out at a time. It is only like 20 bucks a month and you can take out and send back as many games as you want within that month.
I'd have to say I am very happy with my subscription to GameFly and it has been a pleasant surprise.