As a mobile service engineer I live by post codes. When planning a run covering locations throughout a county or counties, it makes a very quick and useful guide to planning out the run. Saved me hours on the road, and coupled with the satnav is a god send.
Whilst this is a very nice quality book, the thing that I've found with it is that it's hard to see the postcodes as there's a lot of detail on the maps. I would have preferred less detail and clearer postcode areas. Otherwise a nice book that gives all the postcode areas at a reasonable cost.