I'm right there with Mirage, some of the Japanese players are total D*CKS! I've met one who was willing to team up for the behests missions at camp, but outside of that they're mostly solo'ers and nationalist douches who think they're being cute using the "language barrier". Of course, some of these people may genuinely not know any English, but I've walked around only to come back and see them talking feveratively in English to another player (actually happened to me in Ul'dan). Most English speaking players are pretty cool, answer my questions and help give me the run around of things. EVEN EUROPEAN PLAYERS have helped me out greatly in the past (when I was first starting out) and even though some of their English was broken it was far more enjoyable and atleast they're trying to help you out.

PS. I'm not saying the majority of the Japanese players are like that, but there are definitely some odd apples that ruin the immersive MMO experience. Don't get me wrong they're are plenty of english (-speaking) assh*les out there too, but in a game with such a large Japanese community, the Japanese players stick out the most when it comes to being rude and ignoring others.