PN, the Sovs had something no one else had. Superior manpower. Thousands of Soviet sappers died just laying down bridges over the half frozen Elbe, yet it didn't even count as a blip on their orbat.
The only question west of Berlin is morale. To the Sovs, WW2 was the 'Great Patriotic War'. The Germans had deceived Stalin by breaching the Molotov-Ribbentrop Pact, and Stalin was pissed off completely.
After conquering Germany, morale may have been different if they were ordered to keep marching.