The thing about teasers as opposed to trailers is that you generally don't get a strong sense of the story. Instead, it leaves with an impression, a sense of the tone.
I'm not sure what the story is about, but I really dig the darker tone that Iron Man is facing. I'm not one who likes darkness for the sake of darkness. But to see his home, the one we've been with for years, destroyed beneath his feet while Pepper is hurled helplessly through the air... that got me.
And as visuals go, I love the idea that the armour has now become a burden literally as we can see in the last shot.
I can't wait to see a full trailer that explains the story to us.