JPN version is region free
To the person who was wondering about the Japanese version, I bought it and it plays 100% on US consoles.
As for the game? It was a totally "not bad" game. Good, solid campaign. Good controls. And yet.. it's all stuff I played before in Halo 3, 2, and Combat Evolved. Still pretty good, but not a 'wow'ing experience. Oh well, still had fun!