One of the best things about Habari is that there is a committed group of people producing and supporting it.
I've personally seen users come into the support channel asking for help with things tangential to Habari's purpose, and walk away with hundreds of lines of custom code provided just to solve their problems. You don't see this frequently in open source.
Apart from that, the underlying design is much more advanced than similar projects. Even while it uses the latest PHP techniques, it strives to build a svelte, usable design. Maybe it's not as visually attractive as some other projects, but attractiveness is not the same as effectiveness.
And all of this is before it even hits a stable 1.0! It's a project that has a lot of promise, and I'm anxious to see where its future leads.