I brought A&A 1940 with me on my last trip to China and played with my friends over there. It put the game in an interesting perspective for me hearing things from the Chinese point of view. In their opinion China is too weak but also to strong. While this may sound contradictory it makes sense.
Too weak; from a sheer military standpoint China was too weak to them. Infantry are really a defensive unit and are rarely brought into battle by themselves unless they come in huge numbers. China dose not have enough to mount a truly successful defense and is often overrun by Japan in short order (yes even with the latest set-up changes). Anywhere Japan chooses to concentrate you can rest assured (unless you have angered the dice gods) that the Japanese will go through the Chinese like a hot knife through butter. The trick is to give China enough infantry so that any further attacks on China by Japan will result in heavy casualties for Japan. Now the problem with this is obvious, with it’s economy and objective IPCs China, with more infantry, will quickly overrun the Japanese and push them off the Asian mainland. This is where the too strong part come in
Too strong; The Chinese economy is way to strong (so they told me). With its territories and objective IPCs China can bring in 18IPCs a turn to Japans 26. As was pointed out Japan has numerous fronts which it needs to send re-inforcments to meaning that its 26IPCs will be spread out while China can concentrate its economy against Japan. So, to balance this, and to balance giving China more infantry, reduce the Chinese economy to about 6IPCs a turn with a further 6IPCs from the Burma road.
This creates a situation where China will have massive infantry armies but will not be able to replace any major loss of these forces. Knowing that its primary role is to holdout against Japan, a good Chinese player would be hesitant to throw his mass infantry into battle, while Japan would be hesitant to strike against China knowing the casualties such fighting would incur. If anything it would focus both players on the south-west section of China, around the Burma road(as was the case historically).