This is great stuff for adapting to different screen sizes, but it's hard to see it as the perfect solution to the varying needs of different devices. It works reasonably well on mobile, but still results in a fair amount of wasted bandwidth. And some pages (looking at you, registration interstitial) serve up 150kb+ images that aren't displayed at all on mobile devices.
It may be responsive to my screen size, but it certainly isn't responsive to my data plan.
It may be responsive to my screen size, but it certainly isn't responsive to my data plan.