Yuna's voice acting wasn't bad or anything (she came off as really meek, but that was almost certainly deilberate), but Tidus was irritating throughout almost the entire game. I don't get the impression that he was supposed to be, either. However, I'm not sure it's necessarily James Arnold Taylor's fault, either, since I've heard his work in other cases where he wasn't annoying at all. I get the impression he was given directions that weren't intended to make him annoying, but nonetheless managed to make him annoying.