Go add this, now, to the #1 spot of your movie cue. Seriously, stop reading and go do it. Done? OK, now you can keep reading.
While War of the Century ("WOTC") is limited in scope to "just" the German v. Russian fronts, it one of the best documentaries ever produced in regards to the mentality of World War II. In that respect, it far exceeds the BBC's epic "The World at War" and Ken Burns' "The War." Moreover, WOTC manages to accomplish this in a mere four installments of 45-min episodes.
As others have said, this WOTC is riveting, moving, and wholly unsettling. There is brutally frank discussion about the extremes to which war drives people. Ex German and Russian soldiers talk about how, and why, they killed members of their own armies and innocent by-standers. Civilians, and soldiers, talk about their roles in murder, cannibalism, rape, torture, racism, and total destruction of the "enemy" (who is often hard to define at certain times).
In Apocalypse Now Col. Kurtz says, "It's impossible for words to describe what is necessary to those who do not know what horror means. Horror. Horror has a face
and you must make a friend of horror. Horror and moral terror are your friends. If they are not, then they are enemies to be feared." WOTC, through startling personal accounts, brings the stark reality of WWII right in to the comfort of your cozy living room. Bottom line: This is one of the top 3 documentaries on WWII (or any war) that I have seen. Moreover, it is a dark look into the human nature, and and the extremes to which people can endure.