Online Game rental

any of you guys or girls use one of these service that lets you rent games online and they send them to you, like Gamefly.com?

im so tired of going to blockbuster or hollywood video and they never have copies of games i wanna rent

just wondering if they are worth it as i dont see 20 bucks a month to actually get the games you wanna rent and rent as many as you can in a month is that bad of a deal. just wondering if anyone who used this has ever had problems...