The ITV documentary series The World at War is definitely one of the best series of its type and holds up really well in 2017. There are only two notable demerits to it that one should be advised of before diving in.

Firstly, its coverage of the Eastern Front is a little thin. The series actually covers the Eastern Front better than its contemporaries (and, truth be told, better than many documentaries today) but it relies a little too heavily on German sources and interviews. This reliance in and of itself is not bad, but the voluminous scholarship of the late 1980s and 90s on the Eastern Front (eg David Glantz) has shown the extent to which the Germans overemphasized the "General Winter" and "Asiatic hordes" tropes to mask the fact that the Soviets eventually outfought their German enemies. The state of historiography on the Eastern Front at the time was much poorer in the 1970s than it was today. Although the Khrushchev era saw the advent of much more candid scholarship and memoirs that acknowledged Soviet mistakes and defeats, these works tended to be relatively unknown in Western circles. The works that were more accessible to Westerners, were, in the words of David Glantz:

the most biased, the most highly politicized, and the least accurate. Even the soundest works have been vetted ideologically, and the authors have been forced to write their accounts with the narrowest of focuses. These realities undercut the credibility of these works (fairly or unfairly), permitted German historiography and interpretation to prevail, and, coincidentally, damaged the credibility of those few Western writers who incorporated Soviet historical materials into their accounts of the war. These stark historiographical realities also explain why, today, sensational, unfair, and wildly inaccurate accounts of aspects of the war so attract the Western reading public. [followed by a endnote mentioning Viktor Suvorov and Icebreaker]

Additionally, ITV was also unable to gain access to the surviving senior level Soviet decision makers. Both Zhukov and Molotov were still alive during the documentary's production (although the former general was in ill-health) but were not among the witnesses ITV interviewed. The result was The World at War's Soviet voices are often mid-level or lower functionaries with less of a big picture understanding of the conflict.

The second deficit of the documentary series is that there is no discussion of Ultra or other codebreaking efforts. Ultra itself only broke a few weeks after the last episode aired with the publication of the book Ultra at War and official UK acknowledgement of it. While there were other books that alleged Allied codebreaking, most notably in Poland, The Ultra Secret was a landmark book. That means that some of the episodes, like the one on the Battle of the Atlantic or the Battle of Midway, are missing a vital piece of the narrative puzzle.

However, these demerits are relatively minor in light of The World at War's many virtues. The interviews with direct participants came at the right time as many are quite candid and it's one thing to know Primo Levi from Survival in Auschwitz, but another to see him talk about the Holocaust directly. The graphics, although dated with a seventies aesthetic, are clear and intelligible (another virtue not often present in today's documentaries!), and the stentorian narration by Olivier is top notch. It also has an incredibly impressive scope; when I rewatched it just a few years ago, I was surprised at just how much of the war it covers.