While I don't hate it, it's definitely the weakest of the three films. Bane's annoying voice, some plot holes, and especially the dopey bomb countdown ending hurt it.
Begins is by far the best of the three. Dark Knight would have been really good if they hadn't forced the "Batman sacrifices his credibility to save Harvey's memory" thing at the end. That kind of ruined an otherwise excellent film for me. I know they were following the Frank Miller story line from the comics, but by combining the Joker and Two Face story lines, it caused the ending to make no sense.