I guess tastes differ, but I personally find the passive-aggressive tone pretty off-putting. Especially, when looking at the table of contents and sample pages, the 100p material seems to be more or less on par with Effective Go or other more practice-oriented books on Go.
There is nothing wrong with that - I am sure there are good lessons in there - but the whole car-salesman vibe the author conjures up works counter-productively (at least, to me).
It's probably equally true for Effective Go.
In general, buying a book teaching you about a topic is often going to be much cheaper than acquiring all the relevant experience on your own through trial and error.
This is a great sales pitch.