The common complaint that I have seen, is that it is a journalist's work not that of a historians. Being that it is a journalist's work, there is a tendency to editorialize. Its not that historians don't value the views of the "man on the ground" the opposite is true, historians love when they have access to the views of people who witnessed the events firsthand. Richard J. Evans, a vocal critic of Shirer's work, cites him multiple times in his books on Nazi Germany, because Shirer was on the ground when many of these events were happening and so his first hand accounts are valuable. The problem comes when Shirer moves away from first hand accounts and adds his own analyses and his own ideas about history. He angered a number of historians, especially German ones with his retelling of German history and culture, and many historians felt he lacked a proper understanding of German history. Here is what Richard J. Evans says about the work in his book "The Coming of the Third Reich"

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 despatches 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

Shirer felt the views about his work were unjustified and assumed that it was simply a case of academics being opposed to a journalist writing history. Shirer wrote another book about the fall of France's third Republic and in the preface he thanked:

a number of eminent French historians, none of whom share the disdain their American academic colleagues have for former journalists breaking into their sacred field — that stupidity is unknown in Europe

So basically Shirer wrote a readable work, with a lot of valuable first hand accounts and interviews, but his understanding of history and the historical method is flawed and that is what keeps his book from being (in historian's eyes) anything more than introductory read.

Also, then what is a good analytical text about Nazi Germany that most closely fits the niche Third Reich tries to occupy?

Why couldn't it be seen as more of primary source and taken with the grain of salt that all primary sources have to be taken with? The mind set of the time that it offers is just as important as the events themselves. Otherwise we are just looking back at the facts through our own lens and will end up misinterpreting a lot of the events.

In "Midcentury Journey" Shirer talked about how his attempts to write about the reasons for fall of France were met with a combination of patronizing ("But Monseur, you are not qualified to understand the French army and the rivalry between the Calvary"..etc etc) and face saving ("It was not my fault, I was in favor of tanks/planes/etc"). I have read much of the arguments against his work , and I find that the criticism of Shirer still falls into of these two camps. 1-He says means things about the Germans. 2-His experiences contradict my theory that I am pushing (or paid to push) and is inconvenient.

In 200 years time Shirers' book will still be a required reading to understand the 20th century. I can't say the same for his detractors.

For a small bonus, this segment from the end of the 'Babylon 5' says this all pretty elegantly

Critics Schmittics....

From my perspective, it's the weaving of the core elements of a large series of interrelated events, over a number of years, between many different parties and in many different places.

An enormous amount of research and hard work has gone into making a fairly accurate and cohesive picture in a fluent, chronologically coherent and mentally digestable - and engaging narrative.

Engaging is a good word for this.

It's an emotionally stimulating read.

It's a really interesting composition.

The truth be told - that WWII was the most documented event in history and this is like a very condensed version of the essentials.

It's a good blend of the core elements and with enough flouishing to put some meat on the bones.

To give it a bit of mental succulence.

The reason why I have read it and reread it a number of times, is because it's a damned good book.

It's a really impressive piece of work.