Zigūr, I agree with what you said here to
Leaf:
Leaf, I think you've made some very interesting points here, which tie in to the idea of the "Hobbit" films as a prequel to the other films as well as being an adaptation of an existing text. What that leaves me with, of course, is the feeling that in my opinion they're not terribly successful as prequels to the earlier films.
One particular problem I had with the
Hobbit films, which made them worse than the
Lord of the Rings films, was that the first group didn't even attempt to give an idea of the size of Middle-earth. The second category of films, for all (in my opinion) their many faults, gave the audience the fact that Middle-earth was big; and if there was a long distance between points A and B, it was going to take a long time to travel between the two, even if you were in a hurry.
I didn't see any attempt to deal with this in the
Hobbit films, particularly regarding Mirkwood. It wouldn't have been too difficult (and there was certainly the time to spare!) to show how big, dark, and mysterious the wood was, and how few safe things there were to eat and drink, not to mention the enchanted river.