Hi Tim
The icons are prettier, and that's about it, as far as I can tell. I won't be buying 5 after my trial hours are up. maybe it's worth it if you are some sort of geo-architect, but otherwise I don't see the benefit. And the way Layers are now handles is very annoying; unless you have a huge screen at high resolution, the Layers dialogue box is always in the way, it doesn't even roll up. There has been a lot of moaning on the SU website about that, which one of the SU staff (presumably the lady most resposible for that particular decision) has been defending vociferously.
On the plus side of SU, and there are many, I've recently discovered the Bezier.rb script, which, whilst it is not as powerful as Autocad, is, nevertheless, a pretty good tool of use to us woodies.
Cheers
Steve