Google+ users can now download full size photos as long as the owner allows image downloads.
Photos on Google+ can be up to 1282 pixels wide, as opposed to Facebook's photos, which max out at 960 pixels wide.
When viewing a photo, click "Actions" to open the dropdown menu and then select "Download photo."
For users who don't want viewers to be able to download their images, click the gear icon to open G+ settings. Scroll down toward the bottom of the page to the Photos section and deselect the box next to "Allow viewers to download my photos."
CONTACTS & LINKS
Dave Cohen, Google+ Photos Technical Lead