Have given it a whirl on 3 images on the PC. There only appear to be 2 really new features:
1 - The auto-heal brush is simple and effective for removal of sensor dust and bits of gunk in unimportant areas; not yet a fully controllable stamp tool
2 - The selection control point is somewhat enigmatic, maybe works on the type of pic in the review or manual where there are objects of strong colour with strong edges, but on landscapes it is difficult to see what advantage it has over previous selection methods apart from opening up possibilities of creating and saving masks rather than relying on the duplication of a step including a selection and/or linked enhancements; need to wait for 3rd party tutorials on that as the manual is of little help.

Against the improvements, the interface (PC version) is pretty grisly. Fewer floating pallettes, slide bars of so subtle a grey they are near invisible and a PS style tool bar. Yuk.

There seems no obvious distinction between operators in RAW and others, the Exposure Compensation now being in View NX style 'Quickfix' section. Also more of View NX stitched into the browser part.

For speed, using a Dell dimension 2400 nominally 2.4x as fast as my ancient powerbook, the transformations appeared slightly faster, but against that, getting the tools in place if anything slower and overall less certainty as to whether it had finished doing whatever or not yet. In 1.3.2 on mac it covers its slowth by producing a preview of lowest resolution it can (intelligently) get away with and beavering away in the background on the full works; OK unless you are doing things needing 100% scale. NX 2 on PC seems to wait more until it has the 100% job available and the activity wheel meanwhile also an incredibly subtle/invisible grey.

I don't think I will be barging anyone else out of the way on the rush to upgrade immediately. Maybe see how soon really informative tutorials augment the rather basic manual and what the interface is like on Mac