I am currently training to be a counsellor and became interested in attachment theory after reading about Psychodynamic counselling. I believed that attachment theory could be related to my own personal experiences.
I have to admit the first few chapters were quite hard going as Bowlby talks about research and the gathering of data, but once you get to Chapter 6 and he starts talking about the findings of the studies then it becomes more interesting and easier to read.
It covers studies on adults who have lost their spouses, parents who have lost their children and carries on looking until we come to children who lose their parents.
I highly recommend this book. It is extremely interesting and I believe people in general can learn a lot from it. I will be going on to read his other volumes, most definitely.