What has constantly bothered me about LXD is how heavily tied it is to Ubuntu. With Docker, you do not need to worry about moving to another major distro like Fedora, CentOS, Debian, etc. - it's officially supported and readily available. The LXD answer to this is "snaps", which are a whole extra packaging system and yet
another Ubuntu technology you have to invest in - making you start to wonder if you're swallowing a spider to catch a fly.
What then increases my concern is that the two other major technology pushes Ubuntu has made into the wider ecosystem - Upstart and Mir - have both failed to take off.
Adopting a niche technology - especially for something as fundamental as a hypervisor - is already a hard choice. The LXD team is making adoption even harder by not offering official repos for the major distros.