The virtual city of GTA 4, called Liberty City, bears a lot of resemblance to New York City. PC Games Hardware compares the nighttime streets around the Times Square of Liberty and New York City.
Mouseout: game graphics Liberty City. Mouseover: real life New York
The screenshots of GTA 4 mainly originate from the 3D Center forum, the pictures of the real world are from the private archives of PCGH editor in chief Thilo Bayer. Have fun with this visual comparison.
Played about 4 or 5 hours of GTA4 without doing the story and have to say it does create a very real world feeling... feels warm and keeps on dragging me back into it.