Well, first of all, Warner Brothers has said that JJP can't use any of the stuff from the third film until the DVD comes out. That's a problem right there. Plus, I think they've been tweaking the game based on all the feedback since Expo, and that's created design and layout changes that required holding off on ordering parts. Now, AFAIK, everything is basically the way it will be in production, so they're waiting on all the parts to arrive so they can begin assembly.
The only unknown is that Jack has said he was holding something back from the Bag End area, and of course, we haven't seen the windlance button in action yet. Other than that, I think the game is what it is.