It was introduced a bit earlier than 16.04LTS, but the desktop support really came a bit later than that LTS release (around the time of the point release).
I have been using it since then, but then again I am one of the developers of snapcraft.
Regardless of my affiliation I really appreciate having a base system that is relatively static and have my apps just roll, and if you don't want to roll too far, you can stick to a major release if the publisher of the snap provides a channel with a track you can subscribe to (instead of following the default track, `latest`). If things go ad, you can always revert, which is a big plus from my perspective as it is clean and per snap.