This, for the most part, is a useful book. I'm not sure that the later chapters and appendix, aimed at Apache module writers, is worth the space and, presumably, the extra euros on the price of the book: this kind of stuff is best left to on-line resources.
The book has lots of good technical stuff, but I'd have liked to have seen more practical advice about running a busy web server.
I also found an unevenness in what was assumed of the reader: a section might begin assuming almost nothing and would then end with some cryptic remarks, wholly unexplained.