A friend who was working on the new Hulk movie, told me when the original trailer went out that that effects and render for those shots were hastily done, and that they will be rendered for the final trailer. I thought it looked great, but the way he said it seemed like he/the higher ups thought it was crap.

Well maybe they were right, I watched the updated trailer and didnt notice alot of the changes, but i then read a article by Alex Billington located here

Heres an image liberated from the linked site, the side by side comparison is surprising. Almost everything has changed, hair, clothing, character pose, bg lighting, character lighting. While the original has more contrast and really makes Hulk pop, the bottom image seems more natural environmentally. I suspect that now that a lot of the movie is starting/already rendered theres got to be a lot of shot to shot matching accounting for the less dramatic render. Just my opinion but check it out. Shows you all the detail that has to go into rendering one shot, let alone an entire movie.