Subsequent open operations on the object will fail, until the handle is closed. From examples like this, I conclude that Williams is adding very little in his description. Of course, I could quibble about the assumptions. But quibbles aside, I'd rate the examples as one of the book's strengths. Williams's writing is clear.
Chapters end with a lengthy summary, and usually contain several examples.
Thus, I noticed that the Winsock in-depth discussion said nothing about what happens if, say, the recv buffer is smaller than the message size. So, I'd be reckless to try a real Winsock project without reading another source. Williams is honest about this. I think that a similar statement would apply to all of the topics he tackles. I have above-average or average knowledge of C and Windows.