I was completely unaware Narnia was filmed. I'd say I'm mighty curious, but not excited and a bit wary (knowing Lewis' attitude towards filming of literature)
To stand in 'compare with Tolkien' line, I'd say that when LoTR was being filmed, I was mighty curious and aware lo-o-ong way before and excited (despite knowing Tolkien's attitue towards filming of literature)
Since I have just got my new boxed set of Narnia, I'm likely to get back to this topic with more to say later