Thank you for this wonderful plugin.
I have set up about a dozen of sites with it.
The plugin works as expected and described.
There are a few features I am missing, i.e. it would be great if end users could have criteria to fine tune what type of posts they get push notifications for (i.e. per category, per tag, per keyword in headline, per keyword in message context).
Also, a widget or a short code with details on how many people have subscribed to the push notifications would be nice to have.
I hope you will consider some of this for future versions.
At this time however, I can only say: thank you! :)