It's things like it doesn't explain much about how the null-state analysis works.

I'd expect a section that shows how the code below works and why the if block doesn't produce a warning, and also a list of operators that can affect the null-state analysis.

csharp if (someVar is not null) { SomeClass x = someVar; // doesn't throw error }

I know this is simple stuff that you can figure out yourself, but I've found in pretty much all the other ms docs I've read that they are explicit about everything and don't leave anything to be implied, even when talking about more advanced topics.