This was required for my psych rotation and initially I almost didn't buy it (many classes have extra texts that you don't really need - I thought this might be one...) However, our professor emphasized that the psych dx in regular nursing care plan books aren't right & don't have all that pertain specifically to psych/mental health and lack correct interventions.
As it turns out, I used this little book significantly more than I used the primary text for the class! It has info on the various psych drugs with indications & things to watch out for, info on appropriate communication styles when dealing with individuals displaying particular behaviours incl. therapeutic communication, descriptions of all the various defense mechanisms etc. It's really worth the $$$.
This is one text I will keep beyond nursing school for easy reference to all things psych.