I don't think Giles was ever out of character, but he was given short shrift, especially toward the end. All that wasted effort on the red herring--is he or isn't he?--of whether he's the First's apparition, when with the council largely destroyed, he could have stepped into the vacuum and become a huge power player of consummate skill, manipulating events and people, taking up the reins of command and coming to a *real* clash with Buffy--and then both of them coming to terms in the aftermath, as they build new alliances and authority systems and traditions.
Yeah, it's all about the what-might-have-been now.
