Have you ever run cycles before?
I ran NPP a few years ago alongside Primo. Killer combo. I got huge gains from it. I have no interest in it now, as I no longer desire to get bigger, but if size is what you're after you'll love NPP. It also promotes a good feeling in your joints like it's long ester brother, Deca.
I didn't experience any physical effects really...however, I turned into a raging bitch. NOTHING has ever shortened my temper like NPP and I've done tons of cycles.