Short review: I intentionally read this with CS Lewis' Letters to Malcolm because I thought they would complement one another. But I was wrong. Letters to Malcolm showed a personal, intimate side of Lewis and was great at giving us Lewis developing thoughts and working out ideas. Peterson is writing composite letters to a composite character. These were flat and a but curmudgeonly. There are nuggets of good stuff here, but all of it is better in fuller treatments in his other books. I am a fan of Peterson and this is the first book of his I really didn't like. But I didn't and think you should skip this and read Letters to Malcolm instead
My full review on my blog at http://bookwi.se/friends/