I think the helplessness of the second act is what really sets the tone for the fast and furious third act. The scene in particular where the agents get hung on the bridge, intercut with Bruce throwing a rock at the TV was brilliant. The slower pacing and desolation helped enhance the idea of Gotham dying a slow death, which is what Bane and Talia's plan was all about.
I dunno, I really love the second act. It's where the movie gets its epic mojo IMO. The cameo from Ra's, the flashbacks. I remember being entranced by it when I first saw the movie. The Bruce stuff really brought things back to that glorious first hour of Begins for me. All culminating with one of the most cathartic moments in the trilogy, Bruce's ascent from the pit.
I know I wasn't the one being asked, just wanted to share