The greenness was cool for about the first hour, then it just got annoying.
Perhaps if everything wasn't "all green, all the time", I might have appreciated it more.
I would much rather have the orange tint of the Mojave than the green tint of DC.
Well, in actuality, I'd rather have neither. I'd like for my color palette to be as "realistic" as possible. One reason why I'm playing with http://www.newvegasnexus.com/downloads/file.php?id=34888
I loaded up Fallout 3 to try to figure out what green tint you guys are talking about but the only green tint I can find is on the intro screen and a mental thing from the color of the HUD.
Go to the Mall during the day and look up at the sky. It's very cloudy and has a very noticeable green tint to it. That's "the greenness."
EDIT: For those of you who want to see what "the greenness" is, then just check out this http://www.fallout3nexus.com/downloads/images/2672-1-1243509264.jpg of vanilla Fallout 3 (on the left) and Fallout 3 with Fellout (on the right).