I heard a bunch of my friends complaining how the map is going to be really small.
From what I've heard its 12 Square Miles. If I'm correct, that's about 20sq km, and that's just about the same size as Panau in Just Cause 2.
It takes about 5 minutes to fly from one end to the other in JC2, with the Pell Silverbolt, so if Skyrim has a map that big, it would take an hour or two just to go that far by foot.