This is a short book, based on some reports written for FFI and others, and in that it has the virtue of concision. Hansen covers al-Shabab's history starting with early proto-Islamist movements and groups started several decades ago. It was the best explanation of where the networks that make up al-Shabab come from that I've read, although it may just be that I haven't been following this too closely since the last time I was last in Mogadishu a couple of years ago.
It was packed with stories and trends that reminded me of Afghanistan, both in the way the international actors chose to respond and intervene, and also in the development of al-Shabab itself. For this reason I'd strongly recommend this book to those working in and on Afghanistan. You'll find a rich vein of material that you can bring back to enrich your understanding of the Taliban and/or the past decade or three. (Needless to say, I'm the last person to suggest that everything is the same in every country, and that there aren't hundreds of reasons why comparisons aren't useful in a this-happened-in-somalia-so-it-must-be-the-same-in-afghanistan.)
There are lots of names and places mentioned, and if you're not familiar with at least the bare outlines of the plot so far as well as some of the key players, you might find it confusing. I wish there was some sort of reference in the back to allow you to keep track of all the different people mentioned.
As always, I wasn't really sure I got a sense of the leaders of al-Shabab (or their fighters) as people in this book, but maybe that's one step too far and one in which it's harder to offer anything that isn't highly subjective or just unrepresentative. Perhaps we can look forward to a book of al-Shabab's songs and poems from Hurst in the future?
Overall, though, an impressive collation of information. Hansen has done us all a service in spending time in Somalia doing fieldwork and in taking the time to put this book together.
Buy it here.