[kupoartist]

hmm... I'm in two minds as to just how good Halo looks, and these screenshots are a mixed bag. Sure, The Master Chief looks extremely well textured and lit, but it doesn't really go that much further than that (also, if the video is anything to go by, if you're not the Master Chief, you look ugly. But then, he has the benefit of not having the troublesome problem of Skin which always Ruins a CGI's looks.)
The Polygons have clearly been neglected: there are too few on stuff like the vehicles, and in some shots, they look awfully jagged. Also, the Environments look a little sparse, and pretty bland in the texture department.
I know many people think that Halo 2 has "The Best Graphics Ever", But i'd probably say that as far back as last year, the Unreal (UT2003, Unreal 2) Series broke into better detail. And Half-Life 2 and Doom 3 are even further on from this... if you have the cash of course...

As for the enemy designs... I was never really taken with any of the original. They look pretty enough, but they don't really look scary or realistic. The best designs for any game set in the future aren't outlandish or strange: they are believeable, as if they could logically exist. Stupid levitating costumes are the first sign of unbelievabilty (its ok to be levitaing, but why bother exempting what you're wearing from floating? thats just silly)... and one of those aliens seems to be wearing one.