Who wouldn't like to get the unofficial word on a big complex city? Who wouldn't like to feel that they were going to be able to find the places that make a city memorable, and that they weren't going to stick out as easy pickings while doing so?
These guide books promise, essentially, that you will know what you are doing before you've actually had the experience, removing some of the nasty anxiety of going horribly wrong as you set out to find urban magic. Some of their features are excellent. The hotel section, for instance, is comprehensive and gives several ways of looking for a hotel that might match your needs. Neighborhood overviews are also very fine.
HOWEVER! other aspects are both annoying and silly. Addresses are often wrong; hours of operation ditto; information about public transporation is (to be charitable) out-of-date. Nothing quite beats hopping confidently onto a bus with a pocket full of dollar bills, only to discover that busses only accept tokens or quarters.
They don't do badly at explaining what attitude you need to take to manage in New York, but neither do they do well. They hint, for example, at the importance of tipping, but do not convey the underlying fact that tipping in NYC is essentially small-time protection money. Not that that's a bad thing. Similarly, restaurant coverage was unimaginative, but maybe there is no way to predict whether a tourist would prefer a very very safe and bland experience, or is more adventurous and would prefer places where the locals eat. Even then, which locals?
This book helped us find a hotel that pleased us. Still, the other aspects annoyed us sufficiently that we left it behind in JFK before we took off.