After watching the preview of the new maps coming out, I don't really see anything spectacular about it. In fact since Call Of Duty 4 I haven't seen them add anything new except for a few different weapons but big deal. I think these games have fallen into the Madden category of being revamped to the same thing every time.
This guy explains the possible burn out very well and offers up an alternative.
Modern Warfare 3 Nothing New | Where's the wow?
http://www.youtube.com/watch?v=9Hc3wmnS_uQ&feature=channel_video_title
He has a lot of subs, so some here might have already seen that.
He makes a lot of good points, I just hate how in one of his vids he was pretty much defending the increase in prices for consoles and games. :(
As for the new maps.. they look like old maps with stuff just moved around.
Zoo feels just like Carnival with the placement of objects and buildings. Gonna take more than that for a better game experience.