Guillermo Del Toro struck me as a terrible fit for The Hobbit, and I was much relieved to find out that Peter Jackson was taking over. Jackson delicately makes much the same point in this interview:
[Guillermo] had designed a lot of the movie. I looked at his designs when he took over and a lot of his designs are very Guillermo. It was very much stuff that you would recognize from Pan’s Labyrinth or Hellboy. It was his artistic vision and I couldn’t make that movie. I looked at his designs and I said the only person who can make a Guillermo Del Toro movie is Guillermo. It shouldn’t be me. I can’t put my head into somebody else’s idea. I have to generate it from the beginning. So really I redesigned the film pretty much. Some of Guillermo’s DNA is in there. There were some things he did that I thought were pretty cool and I’ve taken bits of pieces of his stuff, kind of altering it and changing it as I saw it. But the film was largely redesigned.