We used this Knopf mapguide (along with ones for Naples, Rome, and Athens) during a recent European cruise. We found them to be easy to use, unobtrusive, and easily carried.
We used it extensively during our visit to Istanbul. Streets and places of interest are clearly marked. The book is divided into pop-out sectional maps for each major neighborhood. The construction and paper appear to be quite durable.
My only gripe is where a neighborhood crosses to a different sectional map, it's sometimes hard to get oriented. If the book was just 1/2 inch narrower, I'd give it 5 stars. The guide is just barely small enough to fit into a rear pants pocket, or into a jacket, but it's a tight fit.