This release is a nice upgrade from 2011. It focuses three areas; large team workflow, construction team integration and graphic display. These are what stand out for me...
Citrix Ready Version
We've been waiting for this one for a long time. Work on your Revit project from anywhere.
Now Worksets can be assigned colours. There is also a better worksharing monitor including some chat functions.
3D View Lock
Simple, long standing request.
The ability to break walls, floors and roofs into parts (but still connected to the host). Can be used for shop drawings, precast construction etc.
Now we can save and share material configuration.
This is a nice one. Mix and match Realistic, Hidden Lines, Ambient Occlusion, Shade.
Improved dwg export quality
Not exciting but needed.
Import Point Clouds
I can think of two large local jobs right now that could benefit from this.
This may just bring analysis into the mainstream.
For an in depth look at all of the new features check out this post from David Light's Revit blog.