I've been using this at work to rebuild our internal infrastructure for test, file serving, etc. I was intrigued by its ability to manage disk redundancy via DRDB, though I haven't really tested the instance failover features. So far, I've been focused on getting it working nicely for Ubuntu guests. It's pretty cool to bring up a fresh machine with the latest packages in a few minutes. It'll really come in handy when I start working through configuration management and deployment automation for our apps.