I've had a bit of a historical interest in the war on the Eastern Front since childhood. The attempt at historical accuracy in this movie was much appreciated, although I'm not an expert. The battle scenes might seem a little slow to some, but when you compare it to actual war footage it's not really. Hollywood movies tend to speed things up for extra dramatic effect.
There is an air attack scene by Stukas dropping what appear to be barrel bombs. I guess that must have actually happened. But that scene ends with a Heinkel dumping it's load on the front line. It's a bombing scene that is high budget and impressive, clearly not CGI. It reminded me of that bombing scene in Apocalypse Now where they had only one chance to get it right due to the cost. I expect that was true for this given all the explosives and damage it actually did.
As somebody else pointed out the Germans were highly trained and the Russians usually lost more people in confrontations. This is reflected in the movie. Unlike some Hollywood movies where a dozen or more German soldiers are killed for every allied soldier. It also shows realistic tactics used by the Germans to deal with a Russian ambush by fighting while repositioning to flank their artillery.
It shows women right up there on the front line. That was authentic for the Eastern Front. Completely unheard of on the Western Front.
Yes the dialogue is pants and it's clearly hyper patriotic. But then how must our war movies seem to them? Despite this there are no happy endings here and a very worthwhile watch to see the variety of German tanks, the artillery tactics and the realistic location.
Although not the same type of movie, and not in the same league, it has given me the idea to re-watch Klimov's masterpiece of war horror: Come and See. If you haven't seen that one I very highly recommend it.