Having lived in that general region for a number of years, this was likely to be a book that interested me. However, I couldn't bring myself to read it cover to cover. The older history simply didn't grab me. That said, the book itself is surely a pretty comprehensive account of the history (from a military perspective) of Afghanistan.
I suppose it would interest those with an interest in history, particularly military history. It would also be a very useful read for anyone going to Afghanistan (not just with the military!). It sheds light on the people as well as their history, and for this it should be commended.
This version has an updated chapter on 'Pashtunistan', which is also of great interest. The author concludes with a very interesting concept of encouraging a Swiss-style of governance in the country, drawing many parallels between the two nations.
Generally, a fascinating read for all those with any interest either in history or in that part of the world. Obviously some, like me, might choose to skip a couple of chapters, but I'd recommend it nevertheless.