I purchased this in my local bookshop, hence this isn't an Amazon verified purchase.
This Guide really is brilliant and full credit to the author, Jim Manthorpe for creating a really useful pocket-sized guidebook.
Packed full of useful information from where to stay, to where to eat, the guide's real value is in that the author has clearly spent some time both walking the route and sitting down and answering the questions that most of us really need answered - basic, but important things like - where to eat, where's the nearest cash machine, pharmacy and so forth to detailed route maps. Which, are easy to follow and easy to read.
I'm quiet familiar with the South Downs as I run a cycle hire business covering the area (coastal cycles) and I've found this guide incredibly useful, even though I'm relatively familiar with the area.
Yes, as others have highlighted - things change with the passage of time - and you need to check to see whatever is recommended is still there. For example, sadly and much to my disappointment Arundel Youth Hostel was sold earlier this year (2013) and is now in new ownership and has been re-opened as the Sussex Heritage Christian Centre.
Other things have changed also - as you'd expect no longer are some bus routes running and so forth - but this is to be expected with any published book. But obviously the main information hasn't changed, which is the route and towns and villages along the way.
One thing to note about this route it follows very popular tourist/visitor area - for example, Goodwood with it's festivals of Speed and Goodwood Revival both are huge crowd pullers - 125,000 visitors for the weekends and this puts huge strain on local accommodation. So if you're planning a trip, check to make sure you don't clash with these events as either you'll find accommodation isn't available, or if it is, expect to pay handsomely for a night's bed and breakfast.
All in all a really great book with lots of useful and interesting information.