Detailed granular data that was previously unavailable. The metrics are popular with the suits, and the Minority Report style pregoc info shows me where the hot spots are, where the breakers are inching towards popping, and where one of my CRAC units is starting to slack off. My primary data center used to be something dangerous you'd see William Shattner barely surviving on Star Trek. We now haven't had an outage in over a decade. I've rolled this out to over 50 of our sites, across the US, AUS, MEX, and CAN with plans to hit all the rest of them later. Local IT staff enjoys the new functionality as well - they each support multiple sites, so the ability to relax about power and HVAC is enormously empowering.
I wish the dashboards offered a few more eye candy charts - but this isn't a dog either. Armchair quarterbacks like eye candy and are impressed easily.
Where we previously feared HVAC failures in the summer and breakers popping after a blade enclosure lights up, we now have eyes on exactly where the levels are for temperature and power. We see real time stats and trends that allow us to manage capacity and future growth as well.