How does narcissism compares or contrasts with the "nice guy" complex?

A lot of parallels between the two IMO. The main one being the attempts to control how others view him and feel about him, with low self-esteem being the main driver behind this behavior. Like narcissists, they develop a false self-image(giver, provider, perfect lover) in order to cover/compensate for a deeper, ugly self-image.

Some nice guys(talking about ones with the complex, not any guy who could be described as nice) end up in long term relationships with borderline women. See http://gettinbetter.com/dance.html

And then some nice guys seem to be always chasing after some out of reach girl or impossible situation. The guys have likely developed an addiction to romantic/sexual obsession. And like any addiction, they lose interest in normal things(like available women) in favor of their addiction; finding a girl to obsess over and then spend countless hours dreaming about how great its going to be once he gets her to love him or in bed.