Since Skyrim is the land of the nords and the landscape will probably have many mountains I do feel slightly concerned about the amount of space they take.
In fallout new vegas for example, A mountain was not really a mountain or rock formation nor a hill but more of a huge wall between you and a location. If you managed to climb these hills then you would most of the time be prevented from climbing down on the other side by invisible walls. There was also nothing to be discovered on these hills or anything actually. They cluttered up somewhat around 30% of the entire map. I might be wrong about percentage but still. I like to explore by just wandering in a direction and explore whatever I come across and I frequently found myself walking the same routes and ending up walking past the same buildings and caves because the actual exploring was limited by the huge amount of useless 'mountains'.
I am not saying that Skyrim will have mountains that contain nothing and I think they will be more then just a beautiful sight or just an obstacle. Just worried that maybe they put to much big hills and mountains in skyrim that will maybe frustrate the player if they just want to walk from one location to another.