An Unexpected Journey definitely assumes you know The Lord of the Rings. There's no real establishment of the Shire or Hobbiton and characters like Elrond, Galadriel, Saruman and even Gollum appear without much attempt at an introduction.
I don't see this as a fault but it's interesting that in the books, much of The Hobbit is reinterpreted in light of LOTR whereas with the film, we know where a lot of things are going and we're far more aware what's being set up.