NWO was amazing at the time. It basically single-handedly changed the face of wrestling in North America. All of sudden, a wrestling show looked like a gang war. This fake world where every conflict is settled with violence FINALLY looked like it was inhabited by violent people.
You had sudden, seemingly spontaneous attacks, beat-downs, promos, and counter-attacks. The world felt less scripted, more chaotic. You had to tune in to see what would happen next.
The problem is, WCW milked it to death quick. The elite group of three was diluted with crappy mid-carders, and feuds started being built around what color shirt you were wearing. Worse still, changing shirts somehow replaced heel turns and face turns. Changing shirts suddenly replaced developing characters.
By the beginning of 1997, with Austin and Bret Hart beating the shit out of each other every week, I was starting to feel like WWF was getting to be the edgier, more intelligent program. I mean, just watch these in order:
http://www.youtube.com/watch?v=Pg73pqdFPaA
http://www.youtube.com/watch?v=WA0rjMTBbG0&feature=related
Add in the rise of the Rock, the subversive, anarchistic DX, and the eruption of the Austin/Mcmahon feud, and the the milked NWO just couldn't compete.