Flowdock was and still is a great product. Sadly, it was acquired way back in 2013 by Rally Technologies, which in turn was acquired by CA, which in turn by Broadcom. I think a majority of the original authors exit'ed at some point, and the product has seen rather little feature development ever since.

Lack of competent engineers in the product might also explain the extended downtimes last year. One of them apparently included a full-fledged database corruption where all conversations for a day or so were permanently lost.

I know at least one organization that is so deeply ingrained and accustomed to Flowdock that they haven't even considered migrating to Slack. I, too, still think that Flowdock is a superior product to Slack for the core chat feature. Adding simple video-conferencing would pretty much bring it up to speed with the modern day.