Make no mistake. This is an academic study on the topic of the history of Zen Buddhism. If you are looking for some light reading, stay away from it. Likewise, if you just have a generic interest on the topic as a would be practitioner or from a philosophical or cultural perspective, you may be better off reading something else. Dumoulin's book is a dense volume packed with analysis of this or that particular evolution within the world of Zen, as well as their origins and influences. In other words, Zen Buddhism: A History reads like a clearly academic work geared towards the closely knit community of historians of religion. In that sense, while I am sure it has plenty to offer to those who specialize in the field, I am afraid it does not have much to interest the vast majority of people out there (including me, who decided to quit halfway through). But let me emphasize: do not take this as a criticism of the book, which is actually an excellent book that clearly serves its purpose (an academic purpose, as explained above). So, if you have read a lot about the history of religions and/or are looking to become an expert on everything Zen, by all means add it to your list. Otherwise, I would say there is no need to waste your time with it.

Entertainment Factor 3/10
Intellectual Factor: 7/10