Dimension Improvement in Revit 13

Here's a video that lists some improvements to the dimensioning in Revit 2013.  The first is the diameter dimension, why it wasn't already here, beats me, but I'll gladly take it.

The second may be a little more useful.  Basically it gives you more control over your dimension strings.
The most important thing I gathered from the video was the ability to fine tune and create dimensions.  For example this would allow me to dimension a bay of joists several different ways.

It will be worth your few minutes.  Watch it!