I have used it now for almost 7 years running a law firm. It's worked great for exactly our use case: privileged emails, including attachments, can be time and passworded with legit TNO encryption. I initially used nextcloud/webDAV for our own calendar, but switched over recently to protonmail and it hasn't been an issue. Some storage space is useful. Haven't used the VPN. It's a boutique firm. We have only 4 employees. YMMV