I have been a Protonmail user for close to a year now. Im not a free user, I'm a paid user. I use Protonmail as my custom domain email provider, as opposed to using a standard @protonmail.com address.

For the most part, it works as advertised: encrypted email that the provider cannot read (once it is encrypted on the server), client side decryption, a good set of features, and access to an IMAP bridge (the Linux bridge is in beta test, but you can request access). Their full feature list is quite impressive, though they are a bit expensive.

There are a few issues I have with them, though. And it's becoming enough to want to change email providers.