JavaServer Faces 2.2 is more evolutionary than it is revolutionary. This is by design as JSF 2.0 added a whole bunch of new features as part of the Java EE 6 platform. The Preface 1 from the JSF 2.2 Public Review specification provides a list of changes between JSF 2.1 and 2.2.
There are several changes coming in JSF 2.2 but the big ticket items are Faces Flow, Resource Library Contract and HTML5 Friendly Markup. This video explains Faces Flow.
More about this topic on the video source: https://blogs.oracle.com/arungupta/entry/jsf_2_2_faces_flow