"Do they have broken self worth....one half perceiving they are wonderful the other half thinking they are dreadful?"

They have no self worth.

Now, wait for this because it's a mind twister: 

The NPD has no "healthy narcissism".

The two halves you speak of are the two halves Sam talks about that form the NPD personality: true self and false self.

Or "authentic" self and "hyper idealised" self.

It's a constant desperate fleeing from one polarity to another.

The NPD is created by being torn and twisted between two polarities.

One in which I am a worthless piece of shit, running barefoot and naked to the promised land in which I am God like and all powerful.

The tragedy is of course both are false, both caused by a traumatic break from reality.