I personally think Helm's Deep was just as long as it needed to be. It's just not 45 minutes of blind, pointless battle. There is storytelling, character growth, and evolution in those 45 minutes. It's one of the most efficient and well created battle scenes in modern cinema.
As far as Legolas's action scenes, are you referring to the elephant? That one was CGI, but the scene of him sliding down the stairs on a shield was actually a practical effect done with wire work. The only CGI in that scene was the removal of the wires I believe.
Yes, Faramir's story is tragic but I think that's kind of the point of his story; isn't it?
