It does the main things though - it can check other calendars, people can book into your calendar, it deals with time zones and schedules.
It fits into the valley of "use if you are already using Google stuff alot, but not worth it as a solo feature if you don't".
Cal.com is way better. But then that is no suprise, it's their only job.
They still show up on the mobile version of Google calendar though :/
Edit: doesn't look like there is the equivalent option on mobile, so unfortunately appointments still nukes my phone calendar usability, which is also a deal breaker.