The substantive upgrade for Rhino3D does not disappoint. The new tools and improvements are useful and very stable. Since I use a "Skin" to automate many processes, the software still has more functions that our Jewelers skin has not integrated but I can run in the rhino interface (i'm a version 1 guy so I learned the command lines ;-).. I've had no crashing or other issues. The Gumball interface finally makes sense and practical use of the perspective menu, it is significantly easier to model in the perspective view only.
The only issue that I'm not really happy with is the extrusion of a curve to a solid. Booleans work better in our "Skin" when the extrusion is exploded and re-joined. Otherwise I'd give it five stars!
UPDATE from the reviewer December 26, 2012: "Otherwise,.." I learned that the extrude to solid has a command line option and a default option,.. so now FIVE STARS!