I'm the moderator of the CitiesSkylines and Ukraine communities, and while the site is still young, the developer has put in a lot of love and energy into it. He also communicates and reaches out to the community regularly.
I've been using this for a few weeks. The sub-communities are very empty, but the UI is good and development seems to be moving at a good pace. I think it has potential if they can figure out the community-building side of things.
I joined Discuit at the 3000 member level. The platform is still in its infancy with regards to features, but the developer is forward thinking and has a sound foundation of a product thus far from which to build.
Regardless of available features, a social media platform is only as good as its community and the site developer and admins have done a good job fostering a healthy growth and community based cohesion to make Discuit a welcoming and engaging place to reside.