It's a great book. FOR PSYCHOLOGISTS AND PSYCHIATRISTS. I see a lot of people reviewing this book, who aren't in this field.
This books is for diagnosing purposes (diagnosing others!!) not yourself. If you are doing that, meet a psychologist to get a proper clinical diagnoses.
Psychology isn't just about the abnormal sides, there are fields like Positve psychology which is for strong healthy people. Meaning that everyone needs a therapist.
so read it, but only if you are a qualified individual