It really depends on what you do?
GitHub CI is designed in a way which tends to work well for
- languages with no or very very cheap "compilation" steps (i.e. basically only scripting languages)
- relatively well contained project (e.g. one JS library, no mono repo stuff)
- no complex needs for integration tests
- no need for compliance enforcement stuff, especially not if it has to actually be securely enforced instead of just making it easier to comply then not to comply
- all developers having roughly the same permissions (ignore that some admin has more)
- fast CI
but the moment you step away from this it just falls more and more and more apart and I every company which doesn't fit the constraints above I have seen so far has non stop issues with GitHub Actions.
But the worst part, which maybe is where a lot of hatred comes from, is that it's there for cheap maybe even free (if you anyway pay for GitHub) and it doesn't need an additional contract, billing, etc. Not an additional vetting of 3rd party companies. Doesn't need managing your own CI service etc. So while it does cause issues non stop it also seems initially still "cheaper" solution for the company. And then when your company realizes it's not and has to setup their own GitHub runner etc. it probably isn't. But that is if you properly account dev time spend on "fixing CI issues" and even then there is the sunk cost fallacy because you already spend so much time to make github actions work and you would have to port everything over etc. Also, realistically speaking, a lot of other CI solutions are only marginally better.