As long as you're sticking to the well-established stuff, it tends to be quite factually accurate. I think it's really underrated as a resource for good high-level overviews of fields where those overviews otherwise don't exist at all, are overly technical, or the existing overviews have a lot of author bias.
I'm talking about general overviews of topics, where a good book form at the level you're looking for often doesn't even exist.
You're talking about a classic book that is recognized as a great work.
Nobody's claiming that what ChatGPT outputs is Cosmos. And most books written by people aren't Cosmos either.
And most of the time when you want a basic factual introduction to a field that is at your level, neither too popular nor too technical, ChatGPT is really good at providing that.
Not everything has to be Cosmos.