A really, really good idea

It’s reasonably easy to use – incredibly easy, compared to the effort involved in setting up image sets manually – and saves significant download time. Particularly to mobile devices on slow connections, which is something we should all care about. It’s greatly improved the image-heavy site I tried it on, allowing it to serve impressive full-screen images to retina desktops and yet still be snappy on an average phone. I can see myself adding it to all my installations.

The only reason I don’t want to give this a 5-star review is that I’d love to keep it a secret!