Walsh is the very best type of military historian - that is, both a soldier and a scholar. He's done a good job of putting together a brief, slim overview of the battle of Stalingrad (including the lead-up to it, Operation Barbarossa, and the aftermath). It's most notable for its illustrations - many photographs have never been published before - and for its brevity, presenting almost a bullet-point account of the whole saga.
Walsh sometimes tries too hard to interpret the photographs, and the feelings of the men in them: for instance, many have captions on the lines of "the full enormity of the defeat sinks in...". Conversely, the bulk of the prose is very dry, almost as though trying to offset the picture captions.
The history seems reasonably straightforward, relying on dependable sources. For example, the one German soldier's private diary which is extensively quoted is the very same one used in the magnificent BBC "World at War" documentary. The narrative would have benefitted a little from being more tightly linked to the maps, to help those of us who are geographically challenged, or less familiar with tank battle tactics.
All in all, a good single source for those wanting a reliable overview that's quick to read, and for completists looking for more pictorial evidence; but for those with more time to invest, Beevor's book is more sweeping, comprehensive and dramatic.