It is very, very, very, very, very, very, very, very, very, very cool. Yeah, I wonder what the heck Arwen is doing fondling Aragorn in so many scenes, when she wasn't even really in the second book, but so what--it's nice to have a few new twists. And, God, I know I've made jokes about it, but I really love that brief shot of Frodo looking like a medieval religious painting, white-faced, eyes rolled up in dread to gaze upon whatever part of Mordor he just arrived in. Truly striking. Bravo to the art direction folks.
And an Ent grabbing Merry right off the ground--awesome. Eat your heart out, Wizard-of-Oz-apple-throwers.
I hope that's Gollum that Frodo's attacking with Sting. He's looking awfully vicious and I don't think Sam quite deserves that.
On a sidenote, I never used to call these things "trailers." They were always "previews," and really, doesn't that make more sense? They're not "trailing" anything, the way we usually see them. Oh well. Common usage wins again over logic.