Pros: Can't say yet, since I immediately encountered a serious bug (see below) which made me stop using LR 5... until a new version is issued by Adobe to correct the bug(s) in 5.2.

Cons: Soon after starting to use the LR upgrade (5.2), I discovered that all my edited images from previous versions of LR are now rendered by 5.2 without any blending (feathering) of the spot-removal edits. So, although any new edits work fine, all previously edited images with spot removals are ugly and must be fixed ONE AT A TIME. Impractical to do for thousands of older images. This recognized bug will be corrected by Adobe--eventually. But until then I'd advise users with previous LR versions to stay away from 5.2.