I checked this book out when a Bible study I'm involved with was about to start on the Sermon on the Mount. He gives background information. For seven chapters - Rohr doesn't start dealing with the Sermon on the Mount until chapter 8. There are 9 chapters. No, it wasn't much help.
There were other things that bothered me about this book. It came across as a cross of mystical and liberal. For example, he does not believe that the Gospels were written by the person they're attributed to. He regularly states Jesus was killed. Traditional churches usually say "Jesus died," which is consistent with the Biblical view Jesus gave up His life for our sins; Rohr's method sounds like it was the Religious Leaders in control, not Christ. Shortly after reading this, I heard him referred to on podcasts I listen to as being progressive and new thought.
I recommend this for those who know the Bible well enough to realize what's off base and then read it so you can respond to what doesn't fit. As a book on the Sermon on the Mount, I do not recommend it.