Here's a gist of how it works: Once you've verified your name and address, you can only communicate with people in close proximity. And, like a local message board, you can also post news, offer up items for sale, or get a group of neighbors together for a block party.
I found it pretty useless. It was basically people worrying about strangers and getting into fights about parenting styles.
I also asked Business Insider readers what they thought, and a lot of them agreed with me. One reader in West Hollywood said 90% of her feed was filled out with random messages about a homeless guy who supposedly steals dogs.
But there were some dissenting opinions.
One person in rural Phoenix said he had found a handyman, cleaning lady, and babysitters through the site, and that some people had found lost dogs. Another in Boise said he'd found a handyman and learned useful neighborhood news through the site as well.
And one reader who lives in Oakland said Nextdoor helped people in his neighborhood break up a crime ring:
Stolen cars from a Mercedes dealership in San Jose were cruising around the neighborhoods, casing houses, and looking for opportunities for armed burglary and carjacking. Thanks to Nextdoor, pictures of the vehicles and the perpetrators themselves (taken from Dropcams and security cameras) were rapidly circulated on the Nextdoor site. License plate numbers were documented, and in several cases, OPD was called when suspicious vehicles were sighted. This led to over 9 arrests, and has basically dismantled this burglary ring.
We've not had an incident in several weeks, and the OPD has indicated that the community involvement that was enabled by Nextdoor was key in bringing these thugs into custody.
So, as I mentioned in my original post, whether the site is useful to you will depend a lot on your neighborhood.
But I still think $1.1 billion is a rich valuation for a social network based on neighborhoods, rather than (say) cities or the whole world.