It's great. You are a customer and not the product. There is no advertising. It is business focused but you can just use it as a private person by ignoring a lot of functionality and still have a great package with online office suite, gdrive replacement, a good note taking app. Data ingress and egress are amazing and without artificial borders. I like it and I probably only use 20% of the functionality. For privacy their statement is pretty clear. https://www.zoho.com/privacy-commitment.html

Personally I switched from fastmail to zoho because I host emails for part of my family and zoho offers exchange compatibility so the setup is just as easy as setting up a google mail account on iphone and androids. No fiddling around with cal and carddav.