I've done it a few times, and the ideas put forward in the book are pretty central to my own training philosophy. It's my "go to" for a few weeks post-comp/holiday/etc for a change of pace or to get my strength back up to decent levels in a short space of time. Some people might find it boring, *cough*Crossfitters*cough*, but strength is a skill that needs to be practised. I don't find it boring though - it's only 40 days, each session doesn't take very long, and you get stronger.
If you feel like trying something different then I'd give it a shot. Just make sure you give it the time it needs, as it's not really about increasing your max but more about increasing the frequency at which you can hit 95%, i.e. being consistently strong. It's much more useful to be able to squat 170kg every session without fail, and without having to expend vast amounts of nervous energy, than it is to squat a limit 180kg then struggle to hit 160kg for several weeks afterwards.
“Begin at the beginning,” the King said gravely, “and go on till you come to the end. Then stop.”