A cool new fling was just released: DRS Lens. As stated on the flings website:
DRS Lens provides a simple, yet powerful interface to highlight the value proposition of vSphere DRS. Providing answers to simple questions about DRS will help quell many of the common concerns that users may have. DRS Lens provides different dashboards in the form of tabs for each cluster being monitored.
It tracks things like VM Happiness, balance of the cluster itself, User and System initiated vMotions etc. It truly allow you to dig in to your cluster and it could be very useful during cross cluster rebalancing, or trying to figure out where an imbalance is coming from by correlating different vCenter tasks/events to resource contention / VM unhappiness situations. I hope to see this info in the HTML-5 UI at some point! If you are interested, download the fling, give it a try and provide feedback through the comments, the developers will read those and follow up! https://labs.vmware.com/flings/drs-lens