Yeah Sloniksp, and if I'm not wrong, Stalin sent to the Nazis a proposal to sign the Geneva convention, which they ignored. Another factor is the war in the East was fought with massive armies over a longer front and consequentely longer time. The Soviets had much more ground to cover and resistance to face until Berlin than the Western Allies. And lastly, the Soviets (mainly by Stalin's purges) were not totally prepared for the war. It's interesting that some people who say the Soviets were ready to invade Germany in 1941, frequentely attack the Soviet performance in the wartime. As we can see, this don't have sense, they were really not prepared.