An excellent, well-written piece with a good argument. However... I find myself among those heathens who actually preferred The Dark Knight Rises to The Dark Knight. The explanation as to why requires a full article, and one I may write at some point, but in essence, I much prefer Bruce Wayne's character arc here (especially the pit, and all it's various metaphorical applications). I think The Dark Knight works best when it is taken as part of a larger story. To the points you raise about Bane, I'm not sure I felt particularly let down, as I suspected Talia all along. But again, this requires a full article to explain.

On the subject of ambiguity, I wrote this piece about when I think it does work, if you're interested. :)