As described in the Discourse 1.7 release blog:
Thanks to Sam Saffron, we released an Official Android Discourse app and an official iOS Discourse app. These apps offer native push notifications and a way to aggregate all your Discourse sites in one place.
The apps are free to use for all, but do note that push notifications require special support from Apple and Google respectively, and are currently only available to sites hosted by us. As with all Discourse code, the app is 100% open source.
Notice that last bit about “push notifications … are currently only available to sites hosted by us” ?
So really, all this app is probably only useful if you want to aggregate all your discourse based sites into one wrapper or if you want a shortcut or something on your device. Maybe one day I can recompile the source and implement push notifications via a dedicated app or someone will find a way around current limitation.
Salt to taste, use as/if you will!