I work in Manhattan and the 4g coverage is rock solid. Is all of nyc 4g ? Is say no, not yet. I was in staten island for the day and my thunderbolt was flipping through 4g - 3g -1X. It abused my battery like nothing I've seen before.
So I looked up the area code for where I was 10314. Sure enough no 4g. Thank god I don't live there..
So for those on the borderline 4g area I can see what their issues are.