Their website[1] shows something that looks nearly identical to the MacOS default calendar app (edit: which is a good design to take inspiration from) but no list of features or much else of substance.
Edit: Their docs[2] contain some more info
But how fast is it?
Leaving original up intentionally.
You’ve convinced me to try it out!
Specifically since I was annoyed at getting 2 notifications for every event that was duplicated on both calendars.
And cron actually solved that problem by automagically recognizing duplicate events and only notifying once. I turned off all notifications in calendar.app.
The only other differentiating feature I am aware of is how configurable the menu bar app is.
Thankfully, I no longer have the original problem + I don't like things in my menu bar so I'm probably switching back to the built in app.
I wish notion supported the mac, but they just have a lame web view which isn't any better than using a web browser. Doesn't act at all like a native app.
Cron also runs on Windows. No idea if Windows comes with a calendar.
Windows does come with a calendar, but it's not great.