Surprisingly amusing. I'm constantly amazed at how close some programmers in the 1960s were to agile development methods today. Yes, as expected, some of the arguments are that programmers must do a better job of figuring out exactly what they need to build and how before they begin coding. But it appears that the majority of the conference participants (or, at least, the majority of the outspoken conference participants) believed that things had to be much more fluid.
The book includes McIlroy's infamous, but largely unread, paper imagining a software industry selling parametrized software components similar to a hardware store selling standardized hardware. Amusingly, he used a sine function as an example. Some applications may accept a fast but slightly inaccurate function, while others would need an accurate function regardless of the cost. I find the example amusing because Intel eventually managed to get a fast and very accurate function, which is widely known today.