Yes, I think it is very tricky. As USA and UK you may build 1+1 bomber per turn, bombing Germany to the stone age, while building up a strong fleet. Just the threat of a heavy invasion is enough to fortify France with Italian and German infantry and fighters.
I tried to defend France hard with Italian and German inf. and fighters, and stand with nothing in NWE. Then I simply try to take NWE back with “enough troops” and the whole Luftwaffe. But it didn’t work the last time. When UK and USA goes Germany first, the key is to invade Russia quickly with Japan. (I was one turn to late, last time.)
In my group, we think that Germany is really hard to play.