Being the manly man I am I sat down to examine the reasoning behind this and ended up realizing that the thing that hit me the hardest and made me nearly drop my man card was the MUSIC from the trailer. The classic Elder Scrolls theme, but now stylized like epic "orchestral with choir"(I tried to find a name for the genre, seriously) style.
But when I went back to listen to the theme music alone it really felt like something was missing. At first I didn't think it was the same theme music but a variation. I came to find out that I was somewhat right. The dragon shout right at the beginning of the climix of the music really kickstarted it for me in the trailer, but that shout isn't in the stand alone theme.
Then on top of all that is the sound the dragon makes when it breathes fire. Simply and utterly astonishing.