Not really, Nspawn is extremely promising and is developing fast. Systemd 220 adds support for user namespaces so you can run nspawn containers as non root users.
But containers need minimal OS templates, networking and a way to configure it properly, storage support for things like cloning and snapshots, a way to configure cgroups, and management and those are still not available beyond some basic machinectl commands, and neither is the documentation. Nspawn is going to be a very strong solution, especially given Systemd is now there by default on most mainstream distros, but its not there yet.
User namespaces while letting non root users run containers brings with it a whole bunch of problems on accessing host resources like mounting file systems, networking devices etc that LXC has faced and addressed.
I have an article up on using nspawn containers here [1]. There are a lot of wild misconceptions floating around about LXC. It is actually pretty mature and easy to use, has supported user namespaces since 2013, has advanced networking and storage support for things like cloning and snapshots with btrfs, zfs, overlayfs, LVM thin, aufs, a nice set of tools to manage containers, and a wide choice of minimal container OS templates.
We have a lightweight boot2lxc VM image based on Alpine Linux for those who want to give it a go [2]
[1] https://www.flockport.com/a-quick-look-at-systemd-nspawn-con...
[2] https://www.flockport.com/start/
