I heard that OnLive's graphics suck, considerable lag and wouldn't you much rather have the game forever in physical medium? Even downloads are better. Once OnLive shuts the game off, you can't play your games anymore.
I think it just depends on the person if this is valuable or not. Someone who does not have a "1337" computer and can't afford to buy one and is thus not able to play most PC games would probably find this appealing at least somewhat.
It reminds of the Sega Channel in a way. That thing was awesome.