A false sense of security perhaps?
I'm not saying this product is a bad thing, but we should be careful how much we trust it none-the-less.
Most would assume that an OS running in a VM can't attack the host system, and yet there are vulnerabilities (most recently in Xen 4.1.2) that allow this to happen. There's no reason a microvisor won't have the same issues, especially once it's targeted.
As they say, though, there's far less code for them to keep an eye on than in a full Windows install, so it should be easier to find and fix.