iCloud Photo Sharing lets you share photos with other people and also lets them share photos with you. So, you can share experiences from an event, collaborate on a project, and all without having to individually message photos back and forth. The downside is, of course, you might discover you're not really interested in that many photos from that many people, and the notifications that go with them. In that case, you can easily remove yourself from any shared Photo Stream in just a few taps.
Full story from the iMore Blog...