I was recommended to read Mr. Glantz's work by a YouTuber who makes in-depth videos on the Second World War. I wanted (and still wish) to study more in-depth about the eastern front. Specifically battles, the weapons, the tactical, logistical, and operational ins and outs, along with the commanders who were involved in this theatre of the Second World War. In my honest opinion, I feel Mr. Glantz wrote a very concise and well written book on this topic. If you are looking to study Operation Barbarossa or for that matter the Eastern Front in detail, check out his books, because you'll learn the nitty gritty facts.
I bought this book on Kindle, and I read it within a few days because I was extremely fascinated and focused on the details of Barbarossa and I found that this helped reinforce the idea I had known for so long: Hitler and the Wehrmacht underestimated the Soviet Unions strength, military organization, and will to fight.. Hitler did not view Moscow as important to him as he did the Ukraine, or the Caucasus, due to their rich resources, which Germany was lacking. Blitzkrieg, while at first was a success, it eventually was proven it could not withstand the Russian juggernaut. Germany in terms of its army was not entirely mobilized, but still using horses and traveling by foot, which limited chances for panzers to do more damage to the soviets. On top of this, Germany was not economically mobilized for a total war, and Hitler was already focused on other plans and rejected the option to send reinforcements, winter clothing, and/or solve the logistical problem the Wehrmacht was facing in the east.
All of these things and numerous other things Mr. Glantz wrote about, and reinforced throughout his writings.