Maps data have been updated for Nokia Maps on Windows Phone. To check if it’s available on your Nokia Lumia phone, go to Settings – Applications – Maps – Check for Updates. There’s no changelog available, so we don’t know exactly what the update brings.
The update for New York is 156.5MB. You should probably use WiFi if you’re not signed up for unlimited data with your carrier. You also won’t be able to use Maps while they’re installing. I’ve just installed this on my Nokia Lumia 920. Try it on your device and let us know if you notice anything new.