"We are a federation of microbloggers who care about ethics and solidarity and want to quit the centralised capitalist services." - Quitter.no
This quote says a lot about the Free Software Foundation's continuation of the StatusNet project. It says that they are willing to use their software as a political platform, at least in my eyes.
I used StatusNet before GNUSocial, and was quite happy with it. Decentralized system meant that I could easily run my own instance and other people could connect…at least if my hosting provider allowed access to that sort of thing. Sadly, two-way subscriptions are broken with the hosting package my mate has given me, and would need a VPS or dedicated hosting for me to open it up.
Regardless, even using the public instances was rather nice. The communities tended to be rather pleasant, though some things I said on the public Identi.ca instance were used by FSF zealots to further their political and ideological causes. In general, people were rather kind and open-minded, especially compared to the rather horrid community that has taken over Twitter after it became mainstream.
I have not tried GNUsocial's public servers, but from what I can tell, they are exactly like StatusNet aside from the community. The community seems to be more oriented around the Free Software Foundation's more forceful ideology and political stances, rather than the open-mindedness that Identi.ca had.
However, I did remember that the creator of StatusNet created a new product called Pump.io, which was supposed to be based on an activity stream, rather than the concept of Microblogging. I have an account, but I doubt I will do much with it. I still prefer using my Jappix account for both chat and social updates, and as it is based on XMPP, I love it all the more.
That said, I do not think I will ever see anyone that I personally know abandon something like Twitter or Facebook for another service. The PayPal effect—in which a popular service becomes more popular due to its large userbase, and becomes too big to fall—is rather strong with those companies. On top of that, Facebook's ability to automatically filter topics through machine learning is a very useful feature, and one I myself take advantage of constantly.
It does not matter how much you try to have people try alternatives, as without a majority of their friends joining them, they will see it as useless and simply go back to the other service. I have seen this myself while attempting to convince others to try XMPP over Skype, with only a select few even considering it.
Likewise with Twitter and Facebook. I have attempted to get others to try Facebook, but between misinformation spread over Twitter and the like, Facebook's moderation team being inconsistent on their interpretations of rules, Mark Zukerberg's depiction in the horribly inaccurate movie The Social Network, and other issues from Facebook's general staff, people are very unwilling to even try the service.
I have effectively given up on that, and interop is nothing short of a dream. Meh. Choice is golden, no matter what.