It works surprisingly well, but the AI is still only an AI.
Currently doing a SU only run, on veteran. UK cleared of africa by itself before barbarossa, than failed to do anything in italy (late '42 it sent its units unescorted toward italy, and got destroyed by the remnants of the Italian fleet), but did a nice early landing in france ('43 spring), and slowly taking territory there, allowing me to regain balance and no even do proper attacks. It does somewhat well against japan, taking back DEI and some other islands, but managed to lose three carriers and some surface units not long ago, so the end in Japan will be hard, and Japan getting closer to clearing China (it has 6 units left), and already marching into India.
The European front probably will end in late '44, but the Japan one will need two or more years in my estimate, so it may not be done in the timelimit...