The author has written two books simultaneously. One is a dry military history, packed with details about units, bridge crossings, hardware etc. The other is an account of a massive, humanitarian catastrophe, brought vividly to life by the authoritative use of eyewitness accounts.
The first suffers from a lack of detailed maps and diagrams, which renders half the text virtually impenetrable, as endless accounts of tank units and bridgeheads trundle past without a context. The second is by far the most successful, carrying the whole. It offers insights into the psychology and culture of 20th century europe which are essential, yet previously overlooked, probably because of the 'difficult' nature of the story.
I would have liked to have been able to follow the military story of units fighting across europe on a usable map, and to have been able to decypher the individual accounts of tactics by reference to diagrams and graphics. The author could really have made a decision as to his audience, and published two, separate, companion volumes, each of which would have been much better.