Havin read several books on the attack of the Soviet Union I was eager to watch the movie. I was seriously disappointed. They didn't get nothing right.
To begin with some historical facts: Stalin wasn't the cool headed strategist as he is portrayed here.
First he he denied that his Country was under attack even as a high number of reports of German assaults reached his Headquarter. In his paranoia he was convinced that this was a plot of his own Generals. As he finally realized what was going on, he suffered a breakdown and was not available for his officers for couple of days.
The result was that Russian defenders didn't get any orders and where therefore paralyzed. In addition Stalin had "cleansed" the Military from all able men, so army was weak and without a leader, who was able to organize a counter attack. The Movie somehow failed to mention that.
There might have been heroic efforts to stop the German attackers here and there, as it was emphasized in the movie, but these proved useless against the well planned German assault.
In addition there is terrible acting, bad special effects, a campy Hitler, strange German Tanks that resemble the Tiger Tank which wasn't build in 41 and German soldiers constantly running away from the brave Russians.
In other words: the movie is typical propaganda crap. Don't watch this, if you are interested in military history or you want to see cool tank battles and firefights. In this respects the movie offers nothing.