I have some mixed feelings regarding this book.
On the one hand, there is an incredible and inspiring story of a strong man who made it through child abuse, domestic violence, and racism.
On the other hand, I find this book a bit dangerous for people who are not as strong as he is. It is risky to run hundreds of miles without any preparation or make any kind of extreme effort without doing your homework beforehand. You can literally die.
Also, I find the "personal development" component and the grind set a bit unnecessary and kind of bul*sh*ty. Somehow, those challenges slowed me down way too much. I said that I needed to do them to properly get through the book, but I didn't have the time or proper context. So, it took me days to find some alone time and do the first few until I dropped it. I only resonate with the journaling parts, but maybe it's just me. 
But it's a very inspiring story, and if you pass it through your own filters, you can learn some things about the human body and mind.