I am a lover of OS maps, and of the South Downs Way so I can usually be found with two or more of the orange sheets in my rucksack when I go walking. I decided to buy this product after seeing in in a walking shop and was very glad I did. It covers the whole way and about two miles either side with the exact same Explorer OS mapping you'd get on the large sheets but it means you can get coverage for the whole trail for just over £5 rather than the ~£60 it would cost to buy all the OS maps.
It also has some very basic information on the walk such as distances from one settlement to the next and the Countryside Code. I would recommend buying another guide such as the South Downs Way: Winchester to Eastbourne: A Practical Guide with 60 Maps, Places to Stay, Places to Eat (British Walking Guides)
which will provide a better commentary. Another good feature is the front and back page flaps which have the OS key on, a scale and make it easy to hold your place when out walking.