honestly I actually like gamefly now that I have it since I have managed to afford to play 4 360 games that have are not worth buying but are still decent to play, all for less then $40 over 2 months, where I would have to pay $240 to buy all of them at GameStop, and since I have been a member for 3 months I now have an extra $5 that can be used to buy games I like, and as I continue I can get more discounts. Its a solid system that doesn't require me to pay anything extra for discounts, its cheaper, you don't have to go to a store to get the games, it has all the most recent games in stock, and on top of all that it also offers free music downloads(not of your choice unfortunately) that you can get if you are a paying member, while still holding an online store for games that you don't have to pay shipping for. GameStop is good if you want a game on the day it comes out, but in comparison to gamefly its not good for much else besides Game Informer Magazines(which are always a good read though in my opinion)
oh right there is one disadvantage to gamefly I forgot about. You can't rent PC games, because of the way they run on a PC versus a video game console. So if you want Spore, or the Sims 3, then you will probably find yourself either shopping online or going to GameStop for those.