Recently I found the training session for new features of dynamics Ax 2012 R3 on Channel 9 website.
The important features of Dynamics Ax 2012 R3 are Warehouse management and Transportation management. Presenters described these feature in brief and very precisely. You can explore these features on below link of Channel 9.
http://channel9.msdn.com/Series/Microsoft-Dynamics-AX-2012-R3-Training