New engine, snow is not part of the terrain it is it's own object and you will watch it pile up, weather will be dynamic and change game play, the graphics will allow you to see your own footprints in the snow, combat animations, great guild quests, fus roh dah...
Well the game did have decent combat animations, in my opinion it had great guild quests and Fus Roh Dah worked. So the weather was a PR thing then. I don't really follow games that closesly after their reveal, i only started doing it lately. I rather be surprised by what i didn't know than be dissapointed in what i expected and knew, if that makes any sense. It probably does not. I will follow FO4 abit more than other games, but not past what was shown at E3 and a few interviews with Todd or Pete Hines.
It is why i think that DA:I is a great game aswell, all i knew about it was that we could raise our hand to the sky and some green magic would come out of it and that Varric was in it.