I like its authenticity, what he writes comes from bitter experience - he has been there, done it, survived and he tells it without bull****ting. He knows that hubris has no part in safe flying, he is humble and knows how to describe what goes on inside a pilot's mind. Even though modern aircraft and engines are much safer and more reliable, the basic lessons for flying which he describes so eloquently have not changed. They are the same now as they were then - plan your every move, check and verify every thing you do and, despite better weather forcasting, the weather is still the same as it was then. The elements have not changed, they are as fickle as ever and must always be respected.
The five rules in Jhieminga's link above say it all.