Ralackk: Before everyone dismisses it out of hand think of it this way, Its going to cost just under $180 a year and maybe less if you buy 6month or 1 year package deals. Now lets assume its everything they claim, no delays in the stream and games always running at top of the line graphics. Even with buying the games on the service its not that bad. Consider what it would cost you to upgrade computer parts each year to beable to play any new game with settings maxed out, this will easily be much cheaper.
The downside is it is a service so when you stop subscribing you will not beable to have access to any of the content you already bought. This lack of control means I won't be using it but I can see how people that only want the latest and greatest games might get something out of it.
$180 a year is almost enough for a decent yearly hardware upgrade (GFX card or monitor for example). Add to that the fact that even though you are still buying the games you are also subscribing so like you said anything you buy is gone as soon as you miss a monthly payment. It would be like paying for a Steam subscription. Finally as Ceemdee says it tops out at maximum 720p but it scales to your broadband speed so if you have a slow connection you can expect lower resolutions. Also the games are not played at max settings, Mass Effect was pointed out as using medium settings.
You are getting the performance you would expect from a $100 gfx card for $80 more and you never own anything you buy.