I also recently read this from an experienced Firebase developer: https://medium.freecodecamp.com/firebase-the-great-the-meh-a...
Interestingly, he lists several things that he things Firebase needs in order to be awesome, and server-functions is last on the list:
> 1. Real querying capabilities. Search, joins, the whole enchilada.
> 2. Some sort of references likes MongoDB or RethinkDB.
> 3. Real offline persistence with Javascript.
> 4. Give me moar analytics.
> 5. A cache API.
> 6. Some way of adding server side code without needing to resort to a VPS.