Cisco UCS E-Series Servers have been reliable. I think that's one of the big things. Their hardware has been pretty, pretty reliable. I have noticed some issues with their controllers failing due to the thermal paste drying up and the heat sinks falling off causes them to fail. But that was something we experienced last year. It took almost five years for any hardware failure. And even that was like a $100 repair. So nothing too major.
Additionally, the UCS GUI is pretty straightforward. The server itself is a lot easier to maintain than some of the other Cisco equipment, like the routers and switches.
They are really easy to maintain. I've added RAM to them. I've done a lot of other things with the virtualization.