Been excellent for me.

I’ve got a few nitpicks, but I feel good about moving to Proton from Gsuite paid, where I had my primary domain/email for ages.

The biggest drawback I experience is actually with the calendar. The nature of the design means no 3rd-party app integrations, like Calendly. That’s a drag.

I tried it and I’m rooting for them, but it’s still too unstable to be usable IMO.