EDIT: Apparently Marvel has ordered takedowns on the copies of this trailer -- despite the fact that it's free publicity, and that they for some unaccountable reason haven't yet released a regular trailer for it. So the link above apparently no longer works.
I'm not sure about the (fragmented pieces) we've seen of the plot. Yes, that WAS the reason that Odin originally kicked Thor out of Asgard, but he did it a couple centuries back and Thor lived lives as a mortal which was to teach him humility. Doing all of that in one sequence is a bit much. I'd have chosen to show the exile and then a montage of a couple of hundred years of lives leading up to Donald Blake.
Visually, it looks very good, especially Asgard; they seem to have taken the Kirby and Simonson inspirations and brought them out. The costumes, the Golden City, these look like they came right out of the comics -- and yet they've been done well enough that they do not look stupid.
The Hammer looks very well done. I want one for my own. Though I suppose it won't come with the Power of Thor. And I wouldn't be Worthy to wield it. But it'd look great sitting on the mantel. :)
And the last part in which The Destroyer appears? THAT was a complete surprise and very well done. My main fear is that they may be trying to get TOO MUCH into this movie. Done right they could have several movies of Thor's adventures and even make them part of the Avengers' adventures.
Still, I'm hopeful. The major negative point in this trailer is similar to the major negative point I had with the Narnia movies: wrong voice for the Big King. Odin's voice should be deep, powerful, thundering, not the voice of an old man (albeit a wise man who is clearly also still a powerful ruler).