I've played all of two games, one per side. The AI was more disappointing handling the Allies. I took Espiritu Sonto and won in June of '43. The AI never did mount a large scale counter attack despite having five or six functional fleet carriers and 320+ planes.
It did try to raid (unsuccessfully) my Home Islands which I will give kudos if it was an intentional attempt to draw my forces away from the South Pacific.
Best, -Charleston