Seamlessly replaces images with @2x versions on Retina and other high pixel density screens. Change is performed server side saving requests.
Are you using any form of caching? Unfortunately the plugin currently does not play friendly with caching.
= It works, but the images served on high pixel density screens are the full size images.
Running the Regenerate Thumbnails plugin will help by generating the new image sizes created by the plugin.
The plugin can not scale up images. In order for this to work, the original images need to be at least double the dimensions of the desired image size.