I had similar thoughts about VMware (large installations) back in the day. Weird proprietary OS to run other operating systems? Yet they turned out fine.

This appears to be a much better system than VMware, is free as in software, and it builds upon a free software operating system with lineage that predates Linux.

I say this in the most critical way possible, as someone who has built multiple Linux-based "cloud systems", and as a GNU/Linux distribution developer: I love it!