looks like there is colored lighting on the shot with the zombies, where they have an orange glow on them
i still think it is foolish to judge the game on from such(i think) early screenshots. or from a low quality cam video. but you're right, the poly counts, and more importantly texture quality in those newest shots are most unimpressive. the shadows could also be softer. i have faith that Carmack will make tweaks at the end though.