While I have used this on rare car journeys into the capital, I value it mainly as a reference work and it sits on my bookshelf. I am very lucky as it includes Sevenoaks, where I live, as well - perhaps more to do with a kink in the M25 than the city boundary.
With its excellent mapping at 3.3 inches to the mile - 9 inches to the mile for the centre - as well as planning maps of various sizes, it really is difficult to think of what else AZ could add. Perhaps some more plans like the theatres and cinema ones showing visitor attractions, and perhaps one map of the whole M25 area, unencumbered by the grid of the detail pages, for planning purposes.
I have had my current edition for 10 years and its still in great condition. Perhaps time to get an update in any case?