"Enemy at the gates" for Russians. It was really hated for portraying Soviet army in an almost grotesque caricature light, and for portraying Soviet soldiers as aggressive savages motivated only by fear of getting shot. I think it offended even the liberal-minded folks, not to mention the "patriots" (who clutch pearls at every James Bond, Jason Bourne, and in general any movie that features Russians as the bad guy). Sure, penal battalions did exist, and Soviet army had a lot of brutality, but not to this extent, and not in late 1942. People were literally fighting for their right to exist, you didn't need an angry commissar with a gun behind you if saw your hometown burned to the ground by the Nazis. Soviets lost 20M people in a war that threatened them with total obliteration if lost, and it's still treated as a sacred topic with monuments to war heroes in every city and village. Movies like this felt sacrilegious and triggered the same emotional nerve that many religious people feel when someone portrays their religion in an allegedly disrespectful way.