I like the company, but their email service is nowhere close to being a GMail alternative. A few things that are lacking -
1. Using standard IMAP/POP is only available for Paid users and only on the desktop. Not Mobile.
2. Conversation view is not implemented on their mobile clients. It has been over 5 years - https://protonmail.uservoice.com/forums/284483-feedback/sugg...
3. Their conversation view on the desktop groups messages based on the sender and not always the subject. It results in old conversations being grouped together.
They are working on all these issues, but till then, my productivity was impacted a lot by switching.