So much so that they announced the closing down of another realtime service just last week, the Channel API [1], and are trying to funnel everyone into using Firebase instead. Frankly I'm not sure I even want to look into another Google service as I feel it'll get deprecated in no time as well. Better to use someone whose primary business I'm using.
[1] https://cloud.google.com/appengine/docs/deprecations/channel
One minus point for Firebase is its Android SDK relies on the availability of Google Play services. Most of Android phones in China has no Google Play. So apps can not run even when you do not utilize any of Google Play services. In addition, there is no official words that you can use Firebase services within the great China firewall. It's better to look elsewhere if you have China market in mind.
> The Channel API did not scale well enough for the workloads it was intended for and so did not find wide adoption.
> You can use the Firebase Realtime Database to achieve superior realtime functionality in your application. Firebase is a more robust and customizable solution than the Channels API, and it allows communication with a broader set of clients. It currently supports Android, iOS, and apps, and web browser apps.