(I worked on the GeoFire library)
GeoFire converts the latitude-longitude coordinates of a data point to its geohash, and stores the data in Firebase at the geohash. The properties of geohashes and Firebase play nicely together to make it easy to implement localized search and location querying.
Like the idea of using Geohashes to quickly search for "near" objects and then using the client's processing to extract lat/lngs. I've setup postgis before and it was more of a hassle than I wanted it to be. This alleviates some of the pain :)
Spent the past month putting together an app with Angular, Firebase, and Geo. All three play together very well and have significantly reduced the dev time. Thinking about how much more work I would still have to do without Firebase and Geo gives me shivers.
Very good!. It's impressive how much work you take out of the people that want to develop new Applications/Websites/Services! This is really nice!