I'm only midway through it, but its hypothesis is that (a) we typically draw using preconceived symbols and (b) we can improve the accuracy of our drawing if we learn to ignore these symbols and focus on what we can literally see (ie., shapes and colours). I don't know how universal this perspective is, but as a beginner, I have found the approach to be helpful.

I'm enjoying it. It has a companion workbook that sets up a pretty clear learning path which has been useful.

It's a good book. After following it, I was actually able to draw a recognizable self portrait.

It also reinforced the point that I have zero talent. The drawing that took me hours of painstaking work is something that my wife could sketch in about 30 seconds.