In Newjack by Ted Conover, what do you think are the lessons that can be learned from this book?

There are many lessons that can be learned through the reading of Newjack. This is a first-hand account of what it is like to be a rookie corrections officer in the maximum security prison Sing Sing. It is easy for society to forget about an individual once sentencing has taken place. However, what many fail to realize is that a large portion of these individuals will one day be released. The main question should be: will they be better or worse? Therefore, the overall lesson to consider is the need for prison reform.
To be more specific, we can look at four aspects. First, we can learn what it is like to be a corrections officer and the dangers that are faced each day. Second, we can explore overcrowding in our prison system and the effect it has on the inmate population. Next, we can research different aspects of sentencing reform and rehabilitation programs. Finally, we can discuss the issue of mental illness in the prison system. Each aforementioned lesson can be viewed from the perspective of either the corrections officer or the inmate.
For example, if we focus on mental illness, we can learn that in 2005, more than half of jail and prison inmates had a mental health problem. Is incarceration the answer for those who suffer mental illness? Are correction facilities equipped and trained to handle issues of mental health? Based on the book and my own experience working in corrections, the answer would be no.
Below you will find a link to the Bureau of Justice Statistics that discusses the mental health issues faced in our jails and prisons.
http://tedconover.com/book-newjack/

I'd like to make it clear that the above question is an opinion question.  The lessons that I learned from this book might be different from what another reader thinks.  The key to answering the question is defending what you think.  
One lesson that I learned from the book is that referring to prisons as "rehabilitation centers" is an egregious error.  I'm certain that some inmates are rehabilitated through the prison system, but after reading Conover's book, I no longer assume much rehabilitation is happening.  Near the beginning of the book Conover writes about how the prison system is equivalent to a storage facility for people.  

"Because in reality . . .  rehabilitation is not our job. The truth of it is that we are warehousers of human beings." And the prison was, above all, a storage unit.

The above section of the book really stuck with me as I read the book because it is a very dehumanizing thought.  People put inanimate, non-living things into storage units.  We put things in them that we care about, but we don't care enough about it to have it around us all the time.  That dehumanizing lesson/theme is present throughout the book.  Much of what Conover sees among his fellow guards is that they simply do not view the inmates as people.  This concept really hit home for me when I read that many CO's refer to sick inmates as "bugs" and their medicine as "bug juice."  Conover constantly works to always see the humanity in the men that he is charge of, but it's tough for him as well.  For me, the big lesson from the book is the importance of keeping a person's humanity at the forefront of your mind.