I know about its factual inaccuracies. That it's just a copy of enemy at the gates. However let me explain how this was many kids first exposure to the ussr and what a great job it did communicating through gameplay what the war was.
The soviet campaign takes place last in the game, after the british and american ones. Throughout the game you visit many locations and the mood is an adventurous one. Soldiers remark on celebrating with bottles of wines from french cellars, the beauty of the architecture besides the one or two artillery shelled buildings. And there's never any shortage in supplies.
This quickly changes with the soviet campaign. From the start the design is something that looks like hell. There's no green grass, the sky isn't even blue. Every single building is destroyed by shelling. And what really let you know shit just got real, you don't even get a gun.
They didn't teach ww2 history besides d-day and the atomic bomb, so to a child, this was formative. The creators did an unmatched job communicating the disparity between east and west fronts in the war. It was very clear all of a sudden that the soviets were fighting for their survival in a way the british and americans weren't.
So bravo to call of duty, regardless of how shit it might have become later on, this game will always be one of the greatest achievements of the medium.