Personally, I like the outdoor environments... but I know a lot of people like the urban ones.
One thing I would NOT like to see in another expansion are missions where you have to make sure tanks/trucks/whatever gets from point A to point B safely.
However, on a similar note, I do like going in and rescuing hostages.
Now if we're talking about a patch... obviously, there's some AI and map clipping problems that need to be fixed. My guys get stuck in doorways all the time because they both try to go in at the same time. Also, it seems sometimes during a campaign, the order of my fireteam isn't remembered from mission to mission. Eg, on Bravo I have "L. Cohen, Z. Sharp" in that order. But when I finish a mission, the order is reversed.