Judging from last month [0] and my own comment chain, [1] it is not so good and it is like as if it is guaranteed to go down each month.
> Downtime is not the end of the world.
What if you needed to push that critical change and it is down and all you could do is wait?
What if you hosted your website on GitHub Pages? Maybe you use GitHub Actions (I assume most do here and are paying for it for their teams). Surely people use it for pull requests and issue management as well as for the webhooks and basic git operations.
There are those that went 'all in' on GitHub and use everything on it and are now crying that it is unreliable. This is where going 'all in' makes no sense. (Especially without a backup/self-hosted system somewhere.) Or centralizing everything on it as predicted years ago. [2]
[0] https://news.ycombinator.com/item?id=30841070
You always need a break glass solution for these kind of events, SaaS or self-hosted, something will break at an inopportune time and you need to be able to move forward.