One of the main reasons it is a great resource is also one of the downfalls of it; the fact that you hear from primary sources such as Dönitz etc. Why is this a downfall? One thing you may have noticed is the (edit: almost) complete lack of interviews with those on the Soviet side. Even though very important people were still alive, as well as other commanders on the eastern front.

This skews the perspectives given to those of German commanders, however not only does it do that but it also skews it to those who were left after Nuremberg. Unfortunately this will inevitably be a biased view of the war what with reputations to be maintained and blame to be allocated to those who could no longer speak for themselves.

The vast majority of the war in Europe was on the eastern front, not only in terms of a percentage of combat troops and casualties but also of the civilian impact; this perspective is supposed to be crammed into only (I believe) 3 episodes out of 26 episodes with very limited input from those on the Soviet side of this front.

Another problem is that one of the most important aspects of the war, Ultra, was still technically secret when this documentary was made, and this is a fault in pretty much every WWII history from before 1974. It's hard to give much strategic analysis on Allied/Axis decisions or operations without knowing of Ultra - what might look like a bungling strategic or tactical mistake knowing of Ultra from the perspective of an outsider, may have looked completely fine in the context of the 1940s from an on-the-ground German commander or the upper echelon of the OKW.

There are obvious reasons why some of the above occurred, in the context of the world in the 70s you probably aren't going to have access to Soviet commanders or soldiers, and you definitely aren't going to be allowed to look in their archives. Obviously Ultra isn't going to be widely known about until '74.

Having said the above though, it's still an incredible documentary series for those wanting a first broad overview, as well as wanting to know the (apparent) views of some of those who were actually involved first hand. One problem I have with series such as this is that it tends to present the events in one long and inevitable series - A happened and therefore B obviously happened next as a result etc - however I don't believe this is how one should look at history, especially not something as complex as a world war with all of its moving parts. This is why i say it's good for a first broad overview, because you can then find an episode or series of episodes you were more interested in, for example the war in the Atlantic, or the home front in Germany and the effect on the civilian population, the holocaust or the North African campaign etc and then you can look for more specialised and specific works on those areas.

I'm not aware of any more modern documentaries which reach the calibre of WAW, though there have been several books written which cover the broad spectrum of events such as Antony Beevor's 'The Second World War' or A World at Arms: A Global History of World War II by Gerhard Weinberg (1994 however so it must be read within that context).