Meh, so-so.
Honestly, this movie is OK, but it is severely lacking in many cases.
1, No real sense of context: somebody who did not know about this would be confused like heck.
2. The animations were OK, nothing terribly good, nothing terribly bad. A little bit of fine-tuning would have helped a lot.
3. Music was fine, the others were somewhat muffled and too interchangible.
Overall: not a bad start, but needs improvement.
Also, to settle this once and for all:
As others have noted the British Empire did indeed play an active- if somewhat minor or secondary- role in the war with Japan.
The "First Blood" was the Hong Kong Campaign (as someone else noted), where the Japanese attacked and forced the capitulation of the British/Canadian/Local/Indian forces there.
Next was the Malaysia-Singapore Campaign (as someone else noted). This is perhaps THE greatest British defeat in history, as the Japanese landed with an inferior force and literally pushed the Brit, Aussie, Kiwi, and Malay troops off the Penninsula into Singapore, where they came up behind the guns of Singapore, landed, and pretty much bluffed Percival into surrendering to a somewhat inferior force after the Air Force and Navy had blasted Task Force Z (Repulse, Prince of Wales) off the map.
Next came the Indian Ocean Raid, where the Japanese pretty much decked the rough Allied force of RN, Dutch, American, and Australian forces assembled in the Bay of Bengal and the Indian Ocean and forced them to rebase in Kenya.
While this was going on, the infamous "Island Hopping" was going on, which meant that the Japanese fought Commonwealth forces aiding the Dutch in trying (and failing) to hold the Dutch East Indies, while by this time the RAF was indeed flying support for the Chinese.
However, by far the most influencial part of the Anglo-Japanese War (as others noted) was Burma. This is the Empire's "Forgotten War," and lasted pretty much from the onset to the end, with the British intially retreating into India before pushing back and pretty much breaking the back of the Japanese Empire in Southeast Asia.
And yes, I am obsessed.