New actors taking on old popular roles...

Does it make you cringe when a new actor is hired to play an already established and popular character or do you get excited at the possibilities a fresh face will bring? I have mixed feelings on this issue. It brings a bit more realism to a role to have the same actor play a character all the way through a series. I also like it when studios stick with an actor that I especially enjoy his or her work. However, if I was not impressed with a performance, I can get a bit excited about a change. Sometimes just changing up the cast can turn me off to a series that I used to like (movies or television). Am I the only one who feels this way? How do you feel when an actor turns down the opportunity to reprise a role or is let go by a studio to be replaced by someone else? I can usually respect an actors choice better than a studio decision. What are your thoughts?