Playing as Germany is a fairly well balanced challenge. AI Germany, however, needs to be toned down. In my normal/normal game as SU, AI GER didn't attack me until Spring '42. I loaded to see their situation: they have 685 available IC (more than USA I note), 300 INF divisions, 50 MOT, 30 ARM, 50 GAR, and 20 HQ and with a few misc other division they have 468(!!!) total divisions, and the Luftwaffe is 96 wings. This not counting the ~125 divisions or so they are using from other Axis nations. It's almost comical: they are already out of oil because they get so many free units / get so much IC.
As player SU, they have about double my available IC, are attacking me with about triple the amount of divisions I have, have an air force triple the size of mine, have far superior doctrines, and all the bonuses that WIF gives the AI. I don't think it's going to end well. . .