it's legit not. i've been all over the world, and i've never had the amount of amazing food, culture and overall amazing things to do except in NY city. i truly don't know what people want out of the city, maybe if it cures your cancer by eating their pizza or makes your ugly ex-g/f beautiful and crawling back to you, people would suddenly love it.
but hey, not everyone is built to enjoy the thrills, excitement and adventures of NY. some people like to sit in their barn playing blackjack with their cow bessy while they share their dreams of inviting the girl they had a crush on in high school to the ho-down at the piggly wiggly. then one day they muster up the courage to go to NY, and they spend the whole time in their hotel room or maybe going around a couple of blocks. then they return home and blame the city for not showing them a good time.
it's not about doing party stuff in new york. it's about living. i can't do the things in ny anywhere else in the world, including las vegas (now that place is overrated AF). also, i love amazing food and drinks, so if your idea of culinary delight is microwaved chicken nuggets and a coors light (which hey, i enjoy that now and again too) then i suppose NY is also a let down.
i just have a hard time picturing how anyone can hate the city and whine about it if they truly went out and experienced it.