I am using Cluster Aware Updating and it seems to be working fine with one exception: VMs are not failing back to their original host. Consider the following scenario.
HOST1 has VMs: VM1, VM2, and VM3
HOST2 has VMs: VM4, VM5, and VM6
According to http://technet.microsoft.com/en-us/library/hh831414.aspx the expected behavior is for the cluster to be balanced the exact same way it was before when CAU is finished since the drain procedure takes into consideration the original host. However, at the end of maintenance, this is how my cluster looks.
HOST1 has VMs: VM1, VM2, VM3, VM4, VM5, and VM6
HOST2 has no VMs
I did check that VMs do not have preferred host in their settings. I don't see any errors in the event log but maybe I'm not looking in the right place. I checked the ClusterAwareUpdating and ClusterAwareUpdating-Management logs.