The personality disorders section of the DSM is one of the most controversial.

In particular, while the DSM is categorical in approach (you either have a disorder or you don't, you either have disorder A or disorder B and you shouldn't really have both) it is widely accepted that the presence and absence of personality disorder, and which personality disorder you have is more a matter of degree.

Controversial issues include trying to figure out the dimensions of personality such that we can locate a particular persons personality profile on those dimensions. I guess the most commonly accepted is the 'big five' though there is a great deal of controversy surrounding that.

Their is an alternative diagnostics manual to the DSM called the PDM (Psychodynamics diagnostic manual). Has a very nice section on personality disorders (casts them fairly differently from the DSM) if you might be interested in that...