It's about the same size as Oblivion.
Skyrim is supposed to be slightly smaller but feel bigger with the mountains and things like that.
When has any official statment been made saying its slightly smaller? Todd has said there similar sizes, there has been some member on the forum speculating its slightly smaller and other like myself saying the land area might be slightly larger(because less water compared to Cyrodill so more land, and not even getting into the mountain thing).
TBH I'd like Skyrim to be a bit bigger, say 20-24 square miles, even if the stuff had to be a bit more spread out. Just my preference, it would make the world seem more real. I mean like here http://www.storiedgamer.com/wp-content/uploads/2011/02/skyrim_dragon_triumphant.jpg you have a mountain by the path that is barely taller than a pine tree. It's something that won't bother me too much, but I'd like them to be bigger.
That is part of a mountain, the mountain itself does not even fit the screen you linked!