No, the game is not declining anymore, actually the userbase has been growing slowly and it seems the lauching of the app plays an essential part on the trend reversal.
About the beta thing, the app is not complete yet and it would be a mistake to make it available for new users without all the features available in the desktop version. I guess we will need to wait still a bit. But we waited 10 years for the app, so no problems if we have to wait a bit more for the app to be completely ready.