While Cordelia didn't exactly start out as an important character, she has now become my favorite.  I love the way she cuts through the b.s. and tells it like it is.   Granted she has had to learn some tact over the years, but her straight forward attitude was a much needed addition to the Buffy cast and has become an intrical part of Angel's.  As with all the former Buffy characters, I think Cordy's character has really grown since her departure.  You can really see her caring side, and her great respect for her friends.  Though she has been able to cut through her initial fear of deamons and all things supernatural,  she's still smart enough (generally) to know when not to trust some one.  I think her best episode on this show was the first one when the vampire was trying to convince her he was trying to hire her for a commercial or something.