Marcel Van Den Berg of The Dutch vMafia comments:
One of the interesting new features is Storage Quality of Service . This important feature enables administrators to set a minimum and maximum number of IOPS per virtual hard disk of a virtual machine. The settings can be applied when the VM is running and are activated directly. I understand there will be no support for Storage QoS in SCVMM2012 R2.
Why is this an important feature? Because by far the most performance related issues on server virtualization are caused by storage.