According to Microsoft and Bungie, this trailer is the "first non-teaser trailer of Bungie's eagerly anticipated sci-fi shooter shows an entire squad of Spartan soldiers on the besieged titular fortress planet."
That's not what it is, and that's not what it shows.
This is nothing more than a cinematic, and if past Halo games are any indication, it has absolutely no relevance if you're looking for hints about the quality of the graphics of the game. Disappointing, to be sure.
But, Halo: Reach is still several months away. (I assume the "Falls 2010" text near the end isn't a typo but is rather a play on words. But Halo: Reach is expected in Fall 2010.)
More info can be had on Gamespot. But I want to see in-game footage.