Excerpt from a very positive Lion review
Lion is a giant step in the merger of the personal computer and post-PC devices like tablets and smartphones. It demotes the venerable scroll bar at the side of windows and documents, relying primarily on direct manipulation of documents and lists. It eliminates the need to save your work, automatically saving every version of every document. It resumes programs right where you left off. It can display programs, or an array of all your app icons, in multiple full screens you simply swipe through. And it elevates the role of multitouch gestures and adds new ones.