Walsh's book starts with an introductory first chapter that sets out German aims and means in launching Barborossa, the Nazi invasion of Russia, before, in chapter two, focussing on the advance to Stalingrad. Three chapters then describe the three successive German assaults on Stalingrad, that would eventually lead to the Germans occupying the (by then) bombed out shell of the Russian city that was named for the terrifyingly powerful Soviet leader.
In fact, if anything, Hitler had a retrograde evolution, trading down from the former triumphs of a war of manoeuvre, in which German troops continually isolated and then destroyed or captured Russian forces, in numerous Kesselschlacht (or 'cauldron battles'), and allowing the Russians to force him into an attritional head-on conflict, where the mobility that had brought so many triumphs was neutralised, and his own forces were ultimately sacrificed in an 'infernal cauldron' of their own.
Walsh, a member of the Sandhurst faculty at the time of this books publication - I don't know if he still works there? - is a military authority of some professional standing (apparently he's been on TV as well, though I don't believe I've seen him in that capacity). I was somewhat surprised, in light of this, to find numerous picture captions making what seemed to me like rather basic errors, such as when a pic of two machine gunners is described as a single machine gunner, or Russians are described as sheltering beneath a Russian tank when it's clearly a German tank, etc.
The picture captioning is a relatively minor niggle. More fundamentally, it's quite confusing trying to follow all the factual descriptions, of units, commanders, and geography. This is a frequent problem in narratives of military campaigns. Indeed, it's an area where the requirements of the subject frequently seem to be in a kind of conflict with the medium of writing. Clausewitz's book on the 1812 Russian campaign, for example, is, in my view, an awfully turgid read in the first section, where he does what Walsh does a lot of throughout practically all of this book, which is to, more or less, simply list the facts of the troop movements and engagements.
In terms of literary verve and clarity, this left something to be desired. But in terms of factual content and astute observation, it's excellent. It's also copiously illustrated, which is of course useful for us wargamers and modellers. There are also several maps, and even some interesting aerial surveillance photos. Whether I already read it or not, I think I'll go to Antony Beevor's Stalingrad next, as I imagine (I seem to be coming down on the I haven't read it line!), based on recently reading Ardennes, 1944, that it'll be rip-snorting good read.