I just finished reading this book on the train in today.
Stark's book is subtitled "The Case for the Crusades", and the book cover claims, "The Truth about the Christian Crusades and Muslim Jihad". That should give you a very quick ballpark for what Stark's book is going to be.
It's a fairly quick read, and the writing is quite accessible. That made it enjoyable to read. Secondly, I'm broadly sympathetic to where Stark is coming from: much historical writing about the Crusades is driven by ideology, and Stark's volume is a welcome response to attempts to glamorise Islamic civilisation of the period, demonise Christian Europe, or sideline religion as a component of this important time-period.
Nonetheless, I found Stark's book problematic on several levels. Firstly, Stark up-front admits he is not a historian of this period. Instead, he is writing a semi-popular work deriving all his research from other historians. That would be less frustrating, except for the painful combination of vague references to 'historians', endnotes instead of footnotes, and then those endnotes combined with an Author-Date referencing system to a separate bibliography. Essentially this makes following the reference trail 4-5 times more painful than it should be, and so one hardly makes the effort to check references at all.
Secondly, Stark is pro-West, pro-Christian, and 'pro-war'. I put the quotation marks around the later, because Stark doesn't reveal a position on it. I conjecture that Stark thinks the militant defence of Christians is a justifiable theological position. But his contempt for 'pacifists' is written into the pages of the text. Whatever one thinks of those issues, I think this position of Stark creates a historical weakness to his book: once he has found some justifications for the crusades, his historical analysis of reasons-for and conditions-of comes to a premature halt. More digging could have been done.
What is most welcome is Stark's contextualisation of factors like European technological superiority; religious motivations for the crusades; how, why, and where anti-Semitic violence occured; military and socio-economic reasons for the success of Crusader armies and the difficulties and failures of the Crusader states.
Stark's book leaves much to be desired, but it's still necessary reading. 3 stars.