Obviously, as a Londoner, I have a totally different opinion. I found New York, in a fleeting visit, to be drab and dull. With the exception of a few buildings, I didn't find the architecture to be particularly interesting compared to London, and other than the odd gallery and museum I didn't find much to do there that I couldn't do/see in London. I'd say good for a few days to do the tourist stuff (Empire State Building, Statue of Liberty, Ellis Island) then do as I did, and jump on the bus to DC.
Obviously, living there is totally different, and I am sure that once I found the good pubs and met people I'd settle, but I am not sure I'd find things to do every weekend as I do in London.
*NB I hate shopping, which may be a factor in not loving the city.
Vicky