Actually Revit 2012 have added some new features within to the material panel, but most of the content is messed up. There are my recommendations :
1. The left part of the window containing the list of the materials loaded inside the file need at least a bouton that allow add new material from a library or from another file. Actually the only way to transfert material between files and between users is to use the tool "Transfer Project Standards" which transferts ALL the materials.
2. The material library need to regroup all the properties for a material in Revit (Identity, Graphics, Appearence and Structure), not only the appearence.
3. The Graphic tab need a new "texture alignement" editor. I want to be able to create a pattern over a texture used in the appearence tab and have to ability to zoom in the editor and extend the window to see something and do thing precisely.
4. The "Appearence Property Sets" tab should disappear. It is confusing. Also, the way it actually works (changing appearence by simply clicking) makes it really easy to do mistake. this said, I would really prefer to see the material library has a whole thing as I mention in the statement #2. If you're concerned about the consistency of the common Autodesk Library, I think this library should contain ALL the properties related to the materials of each Autodesk Softwares, then each separated software could read only the properties that is useful for its purpose.
5. Please remove the preview images on top of the Identity and Graphic. The preview should only be in the material tab (when show small or large icons is selected) or in the Appreance tab.
These enhancement should really help to improve the material experience.