Richard Overy's book is a very good example of a strong analysis of the Second World War.
A couple of things, I am missing in his account of the allied victory is two things. One is the role of intelligence, which he himself writes that he do not attribute to having a war-winning effect, and therefore do not single out, but instead mentioning it, when it is important, to his account. I don't think that you can underestimate the value of allied intelligence. The Soviet union had througout the war very good direct and indirect sources as regards German military planning. I Overy puts to little emphasis on this.
Another thing is that Overy puts emphasis on the importance of the weather in the context of D-Day, but he doesn't do it in relation to the Eastern front. There is no doubt that "General Mud" and "General Winter" played a very important role in slowing down the German offensive on the Eastern front.
It is also a very sweeping statement that "he (Hitler) did not consider economics as central to the war effort." (p. 206) Hitler put a very strong emphasis on certain aspects of war economics for instance raw materials. He stopped the advance on Moscow in 1941 and didn't repeat in 1942 because he wanted to focus on the natural wealth of the Ukraine and the Caucasus, and in this context said that "His generals didn't understand the economics of war". He even talked about the reconquest of the Rumanian oil wells in the Bunker in 1945. Eventually, neither Hitler nor his generals had a deep understanding of the essentials of the war economy such as mass production etc., which is also mentioned by Overy.
And all in all, a very good book, which also gave me new information for instance of the effect of allied air power.