There are to be 4 new maps to be released incorporating a variety of tight indoor areas and and larger outdoor areas.
The map in refence to this article, Chinatown is built around a town and will have lots of small alleys and closequarter combat areas between the buildings, although the devs have promised there will still be some sniping spots for long range warfare to pick off the enemy one by one. So overall, a bit of everything.
The four maps are as follows Chinatown, Creek, Broadcast and Killhouse.
I quote below from various sources a brief review for some of the maps:
IGN Says: Of the four maps that we tried, Broadcast was probably my personal favorite. It seemed to do a good job of providing players with different outlets to try and get the upper-hand. I never found myself pigeon holed into going the same route over and over and the skylight certainly provided us with plenty of harrowing moments.
Gamespy says: The first map we checked out was called Creek, and it's one of the largest Call of Duty 4 maps to date. Creek is an asymmetrical map that features a multi-building village on one side and a farmhouse on the other. Despite the trees and bushes that dot the landscape, it's actually possible to see a fairly long distance, making this a great map for those players who love to snipe.
Separating the two landmark areas is a dry riverbed that lies in a valley between a gently sloping hillside and a steep cliff with switchback trails cut into it.
TeamXbox Says: Chinatown has the look of an inner-city neighborhood. Again, mixing the outdoor areas of the street and alleys with the two-story indoor areas of the building makes for a very nice mix of close quarters and long-range style fighting.
A foot note at the end of the article states a mid April release for the map pack and a price:
In addition it looks like we've finally been able to narrow down pricing and a closer release date for the map pack with it hitting in early to mid-April for 800 MS Points with similar pricing for PS3.
hmm new weapons? I hadn't thought of that, but its definitely an interesting idea. Heres hoping some are added. I would also have liked to see a map that was set at night, but looks like this pack wont be including it.
That is highly recommended, if your are into FPS games then this is heaven. I got a new SONY Bravia this weekend and it looks stunning running COD4. I'm tellin ya, you have been missing out these past few months. You won't know how you lived before without having it once you've played it. It's that good. The single player is a bit short and has limited replayability after a few run throughs but the online you can play for months easily.