The Creative Cloud. I don't like the idea myself. $10 a month for Lightroom, Photoshop CS6, and the other adobe tools. I like owning and not renting. Plus I don't like using photoshop. Seems as though they chose to continue LR as a standalone product.
Biggest change I saw from 4 to 5 was the clone stamp. Its great for pimply faced people and portraits, as well as cloning out an occasional distracting element from a landscape. Some of the other new features like the radial filter I could live without.