Only 1 other person with a profile photo in my building (Out of ~500 adults). The entire 'hood (5,000-10,000 people) only has 51 people registered (16 with a profile photo) and no updates since January.
The upside I can see with this is that it's incredibly difficult to replicate what Nextdoor have created and that probably plays a part in why it's now so valuable. I mean the stickyness of a network like this is insane.
It's easy for a WhatsApp or SnapChat to come in, ride off of users' contacts or address-book and build massive social networks to compete with Facebook. How the hell can you compete with what Nextdoor is doing without a significant investment of time, resources, and just grinding it out.
To me, this looks like a classic example of "Doing Things That Don't Scale" and a company benefiting tremendously from it.
I am not sure about you, but if you break it down, knowing that 51 people in your neighborhood will see your updates is still empowering. I live on the corner of Central Park South and 7th Ave, and I get cool updates from the few people that share my area. Sure, this is the same area where apartments sell for 100M, but yeah. And also, I might add the best thing to do is just go to a pub and meet people. Some of my neighbors are truly inspiring.