To be fair, most software is full of bugs, Mojave especially.

I use their standalone program on Ubuntu at work; we're switching from hangouts/meet to zoom for a lot (though ad-hoc stuff will likely remain hangouts due to it only being one-click to start one up). It's pretty straightforward, I've almost never had issues.

I just use their desktop app.

The call quality of video and screen sharing is significantly better than Skype and hangouts.

No, but I don't use Skype for that either.

And though I don't use it with friends (FaceTime mostly fills that role) I work remotely and do use Zoom several times a week for video meetings and screen sharing.