The One True John has taken iCloud Shared Photo Library out for a spin:
Having gone through the process of setting up an iCloud Shared Photo Library, I have to say I’m very impressed with how well the feature has been architected. So far, I’ve only added Jennifer and one of my sons to my iCloud Shared Photo Library, but the initial setup process didn’t take long, did a good job of explaining my options, and went smoothly, adding both of them to a library of 25,000 of my photos featuring our kids and extended families.
I look forward to taking a sabbatical to combine my photo library with my wife’s.