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U mean manhattan or the city of new York? Because I live in staten island so I would say it hasn't got much better but I always have coverage just not perfect coverage. and as for manhattan I'll be there tomorrow so I'll see.
 
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Generally speaking, AT&T has definitely improved in NYC. I have an AT&T iPhone 4 and picked up a verizon model yesterday because I have a few "problem areas" where I do repeatedly get phone calls dropped and low signal. Low and behold, the verizon model barely got a signal in the same area, and kept switching between 1xRTT and 3G. And through and through, I find that AT&T 3G is significantly faster than Verizon when out and about, which has been reported everywhere.

Places I frequent for comparison:

UWS, hell's kitchen/central park south area, and Washington Heights. Also was on staten island yesterday and didn't discern a difference in signal quality near me and definitely saw the same speed difference.
 
I was in Manhattan a month ago. Service seems to have improved over 2 years ago. I would like to test verizon with my new one next time I'm out.
 
The service in NYC has improved dramatically over the last 2 years. They are constantly adding new cell sites in Manhattan.
 
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