This is classic military history, concerned with individual units and battles of maneuver and buttressed by learned appendices including orders of battle and reprinted orders. I actually found it rather fascinating, because although I know a great deal about WWII, the details of the eastern front have always been a bit hazy for me.
It turns out that some of this haze was deliberate; the Soviet Union removed some serious losses from the history books to concentrate on the Red Army's glorious drive to Berlin. In recent years, more of this hidden history has been coming out as some archives have opened up and some new material has been published. In addition, Western scholars including Glantz have been working with the German Army's records and getting at the story from the other side of the front lines.
Operation Mars was intended to be the centerpiece of the German Army's offensive in late 1942. You've probably heard of the Battle of Stalingrad, where the Russians cut off and destroyed several German armies. Well, Operation Mars was the same idea at the same time. In addition to the Stalingrad salient, there was one at Rzhev. The armies there, under the direction of Marshal Zhukov (most famous soldier on the Russian side in WWII -- pretty much their equivalent of Eisenhower), were to cut off the salient and destroy the encircled Germans.
Only, it didn't work that way around Rzhev. The Soviets had a great deal of trouble throwing men and tanks across the rivers and marshes in the area, where German lines were anchored on the terrain. Inside the salient, the German General Model took brilliant advantage of interior lines to shift reserves fluidly, and several German units performed heroic feats of maneuver, helping repel multiple Russian assaults in a matter of days. The end result was that, although the Russians gained some ground, it was at a tremendous cost (perhaps a quarter of a million Russian casualties) and the German lines held. Of course Model later had to pull back as part of the general collapse of the eastern front, but this was not the glorious victory that Zhukov coveted.
It occurred to me while reading this book that World War II is the war that I am most familiar with on a strategic and tactical level. I know, for instance, roughly where Stalingrad is, while I couldn't tell you on a map where to find Inchon Reservoir, Ypres, or Cam Ranh Bay. I suspect a lot of this comes from a teenage involvement with wargaming, when WWII games were dominating that market. But some of it is also that this is still _the_ war that permeates our culture, the one that movies are made about and books are written about. There is a substantial literature on Viet Nam by now, and I wonder whether it will occupy the same place for the next generation as the prototypical war that WWII does for mine.