Of course some bits of it are worse than others, but in a documentation set which must total tens of millions of pages
MS API documentations is awful
is a completely ludicrous over-generalisation.
I
have had particular problems with some of the Microsoft crypto API documentation recently ... but the open source stuff really really
really isn't any better! This seems to be simply a feature of the crypto world - one gets the impression that the geeks who understand the mathematics have been let loose on the API documentation, in both cases, which is obviously a recipe for disaster.