Depends on your needs. It’s reasonable for mails you don’t need instantly or offline, but at the same time should be encrypted at rest. I don’t know if there is a new pricing model now, but I have paid 1€ a month, so basically nothing. If you don’t mind the downsides and encryption is important to you, it’s a very fair price I think.

Payed for 5 years, but now I’m in the progress of migrating to a “regular” mailservice. Problems I have with tuta: The client has become super slow in recent months, it seems to get worse and worse. Notifications don’t arrive or arrive too late (Android). No other way than to use it with their clients. No offline support (or at least it doesn’t work for me). UI/UX isn’t that great either.