Frankly, the most interesting thing of note is that in this age of director-shepherded franchises, the Twilight Saga will end up having a different director for each book. Even the Harry Potter franchise has had four helmers for eight pictures, with Chris Columbus directing the first two pictures and David Yates directing the final four episodes (of course, Alfonso Cuarón directed part 3 and Mike Newell directed part 4 in between). Even if Breaking Dawn becomes two movies, that's still four directors for five movies in a single narrative. In this day and age, where Sam Raimi starts and finishes his personal Spider-Man trilogy, and Chris Nolan seems set to close out his Batman epic, it is a little unusual for the cast and narrative to maintain such consistency while the director's chair is a revolving door. It is one thing when an initial helmer is shown the door or leaves the series after two installments for whatever reason (Batman Forever, X-Men: The Last Stand, Chronicles of Narnia: Voyage of the Dawn Trader),or when the studio wants to revive a finished series with fresh blood (see Rob Marshall taking over the reins from Gore Verbinski in the new Pirates of the Caribbean picture) but it is quite interesting that Summit is so determined not to maintain the slightest bit of directorial consistency with a series that none the less maintains a rigorous narrative continuity.
This isn't a James Bond or Mission: Impossible installment, where each film more or less tells a stand-alone story that has a bare-minimum of continuity from the prior picture. And considering how very different, both visually and tonally New Moon was to the original Twilight (and how more overtly visceral Eclipse seems to be in comparison to both), the only series that comes to mind that even comes close to playing this game is the Alien quadrilogy. Each installment had a wildly different director (Ridley Scott, James Cameron, David Fincher, and Jean-Pierre Jeunet) and thus each film felt completely separated from the prior one, even as the characters and continuity were more or less respected. And considering how loathed (perhaps unfairly) the last two Alien pictures are, it will be interesting to see the critical reception to these last two (or three?) Twilight pictures.