I have no experience with the OpenStack but I would be extremely surprised if anyone with any experience with the CloudStack switches over.

Last time I checked it out, the CloudStack had a homemade ORM, no messaging queue, windows line endings on nearly every source code file (primary deployment platform is linux, I don't find that encouraging) and worst of all, the test coverage was in low single digits. It felt like a project being run by a marketing team, built using contractors and absolutely riddled with bugs. That said, if you're planning to run a private cloud with it and don't mind it falling over once in a while, then it's simple to setup and get running.