It has first-class communications features that Flickr has always sorely needed. Commenting isn't a tiny box at the bottom with awful pagination, you can upvote posts as well as comments, and it has group sharing capabilities well beyond "add to pool".
The photo upload process is also far superior to Facebook, and the photo viewing experience is superior also when it comes to high-resolution, high-quality compression that many photographers desire. Facebook butchers uploads with awful compression artifacts.
I've been seeing a lot of amateur and professional photographers flock towards G+ - doubly so since the launch of Communities.
Personally, I like using Google+ to talk photography a hell of a lot more than I like to on Flickr. That might be telling.