I had intended to use it before I used XenForo, then nothing, then started my own forum software (will probably not be released before 2020, given that it can't do anything just yet).
So, no, I don't really use it. But I had some friendly encounters with the devs, I was one of the first German translators, and I like how well they respond to feature requests. ElkArte was the first forum software which crossed my ways and had built-in OpenID support.
It rose from the ashes of SMF when they made it Free Software and it is the only one of the six or seven subsequent forks that still sees public releases every few months. SMF has moved on, sure, but ElkArte has some former SMF devs and much less bureaucracy. Yet.
Nevertheless, I regularly talk to one of Elkarte's core devs on the IRC. One of our recent encounters reminded me that one feature was missing from ElkArte, so I basically wrote a PHP port from my blog software. No real development work required, only programming. That was worth the time anyway, I guess.