From an earlier answer of mine

Shirer's work is not completely useless; as a journalist, Shirer was privy to a number of small details on the Nazi elite and life under the dictatorship. If historians of the Third Reich today cite Shirer, it is usually for this man on the ground insight. But Evans's critique still holds and it is worth citing at length:

Shirer’s book has probably sold millions of copies in the four decades or more since its appearance. It has never gone out of print and remains the first port of call for many people who want a readable general history of Nazi Germany. There are good reasons for the book’s success. Shirer was an American journalist who reported from Nazi Germany until the United States entered the war in December, 1941, and he had a journalist’s eye for the telling detail and the illuminating incident. His book is full of human interest, with many arresting quotations from the actors in the drama, and it is written with all the flair and style of a seasoned reporter’s dispatches from the front. Yet it was universally panned by professional historians. The emigré German scholar Klaus Epstein spoke for many when he pointed out that Shirer’s book presented an ‘unbelievably crude’ account of German history, making it all seem to lead up inevitably to the Nazi seizure of power. It had ’glaring gaps’ in its coverage. It concentrated far too much on high politics, foreign policy and military events, and even in 1960 it was ‘in no way abreast of current scholarship dealing with the Nazi period’. Getting on for half a century later, this comment is even more justified than it was in Epstein’s day. For all its virtues, therefore, Shirer’s book cannot really deliver a history of Nazi Germany that meets the demands of the early twenty-first-century reader.

This critique is pretty damning. The Rise and Fall of the Third Reich presented a distorted and outdated view of the dictatorship in 1960. Shirer in particular was fond of ascribing the events of German history to a national character. This crude version of the Sonderweg (special path) thesis that had some currency in the immediate postwar period. In a nutshell, the Sonderweg is an idea that Germany's political modernization and development was malformed so that an illiberal order like Hitler's was somehow inevitable. Some of the more sophisticated Sonderweg proponents like Hans-Ulrich Wehler looked at the political structures and socioeconomic conditions of German unification and how they played out over the longue durée. Shirer's Sonderweg lacked this nuance or scholarly methodology. The Rise and Fall of the Third Reich instead produced a caricature of German history and development. The Sonderweg thesis itself is one that has largely crumbled since the 1980s and this was one of the reasons why Evans claims it cannot meet the needs of readers in the millennium.

There are other methodological problems with Shirer as well. For all of his readability, Shirer did not really understand Germany all that well and he often transposed his own American perspective onto events. For example, one of his observations that has found its way into the "Nazis are socialists" crowd is that the Nazis imposed all these onerous regulations on small businesses and the private economy. This of course reflects partly on Shirer's own biases; he falls into a long line of American reporters on European affairs that transpose American values and precepts in judgement of Europe (ie why can't they be like us?). That the German economy was markedly different than the American model is something that Shirer never really considers. German capitalism was already prone to cartelization and concentration well before Hitler turned up on the scene and there was a much greater tradition of openly interweaving the interests of business and state than in the US. Moreover, the Third Reich often moved belatedly against rationalization measures that would impact small businesses and concerns whose lower middle class owners were one of these bedrooms of NSDAP ssupport.

Shirer did a similar thing with France and the defeats of 1940. He argued that France fell so quickly because of internal rot among a French society polarized between a decadent elite at the top and communist subversion on the ground. This inadvertently recapitulated Vichy discourses that explained 1940 and ignored the fact that communist subversion was very small-scale and many of France's generals fought hard in 1940, but were often out of position to do so and hobbled with a doctrine that was ill-suited to rapid changes. But as with Germany, Shirer's American condescension of European politics and mores emerges.

The long and the short of it is there are many, many books on the Third Reich available to readers in 2020. Many of them do a much better job of explaining the dictatorship far better than Shirer. To rely upon a book published in 1960 that presented an outdated and flawed view of Germany even at the time is simply a folly.