I've read quite a few books on prayer, and this is one of the most unusual. It has five chapters and a Q&A section, and maybe it's best to comment on them individually.
Chapter 1 - Different Prayers for Different People. Martinez looks at basic Jungian typology - thinking, feeling, sensation, intuition, and then applies it to what styles and types of prayer suit each. He takes care to say that we should work on the areas we aren't so good on as well as enjoying the areas that we are more comfortable with. Pretty good.
Chapter 2 - Overcoming Difficulties. He goes through a list of common reasons people find it difficult to pray - "God feels so distant" and so on, and deals with them with a lot of pastoral wisdom coming from his decades as a counsellor and psychiatrist. Stunningly good.
Chapter 3 - The Therapeutic Value of Prayer. The focus here is on how prayer can be key for dealing with various psychiatric difficulties (guilt, depression, etc) and for good mental health. Very good.
Q&A on Prayer - Some questions he's obviously been asked - answers are good and psychologically insightful.
Chapter 4 - Prayer: Psychological Illusion? This is the best treatment I've read of the apologetics question as to whether prayer is a psychological illusion. The answer is no...
Chapter 5 - Are All Prayers Alike? Martinez discusses the question of the relationship between Christian prayer, Christian meditation, Eastern meditation, Platonic ecstasy and magic. Helpful.
I guess the unifying theme between all these chapters is something like "Things Dr Martinez has learnt about prayer in many years of being a Christian, a counsellor and a psychiatrist." An odd collection, but one well worth reading, if only for chapter 2. Definitely worth keeping on the shelf to refer to in the future.