How do the various improvements to sharpening in Photoshop CC relate to each other? PM Zorana Gee posted a blurb I found helpful:
Shake Reduction is to remove blur caused by subtle shaking of your camera. Smart Sharpen is about sharpening the existing pixels (2D blurs) – no analysis of image or how the blur happened. They do actually work quite well together. Start with Shake Reduction as it requires the most original data in order to find the blur trace and then use Smart Sharpen.
Update: Zorana points out a detailed article on shake reduction (showing numerous before/after examples) from Andy Trice.