The NYC I remember, and love, from then was dirty, smelly, and culturally adventuresome. It was also diverse ethnically and socio-economically in a not so segregated way.
Today, when I visit NYC, and even Brooklyn for that matter, it feels like a city for the wealthy, and it feels much less ethnically diverse than it used to.
I lived there for a little over a year...agree that Manhattan is not necessarily that inspiring.
I could never figure out what to do on the weekends. It felt like I was always stepping outside into a financial district and all anyone did was go to mediocre & expensive brunches.
Do you enjoy nightlife? If not, you may not enjoy the city as much.
But there are frequent live music shows, good bars of all types, great late night food options (food trucks, pizza spots, Japanese izakayas), beautiful parks (I liked Prospect Park especially, but Central is gorgeous too). And if you're a single heterosexual guy in your 20s, the dating scene is pretty incredible. It seemed at least decent for other orientations too.
But yeah, there are overpriced brunches too. I tended not to do that as much because I'm not really a fan either.