I'm using the beta app and everything is good but it still doesn't support conversation view.
(I have yet to find any open source android email app which looks as modern as proton's, maybe AOSP email?)
They have also bought [SimpelLogin](https://simplelogin.io), the email aliasing service, and promised that SL would be intgersted in the plus plans when SL Is merged into proton in 2-3 months. I'm hoping that they keep multiple domain support, even though I doubt it will happen.
As for proton calendar, its usability for me is pretty limited until they enable syncing with the OS on mobile and offer a Caldav server with desktop bridge. If they would also offer contact sync that would be super!