The NYC version of Zagat is pretty good, although the last couple of years the ratings have converged to where just about everything gets a 20-21 rating and there are few others, which makes it harder to find good places. As suggested before, Chowhound is a great reference.

We used the Boston Zagat guide last year and it did not match our expectations at all. We have found that the number ratings are relative to the area and a 22 in Manhattan is not the same as a 22 somewhere else.