I really like the concept of tunnels serving as possible flanking points.
The idea itself wasn´t explored well enough in Normandy, but I´m kind of hopeful about how it will turn out in Tunisia.
As for the new map of Moscow, I suspect it was heavily influenced by the development of Stalingrad (comparing available campaign screenshots and this new map), and if compared to the rest of the maps, almost looks kind of out of place. One could argue, that it might serve as a gimmick of some sort to people who are not interested in Stalingrad itself.
But it is a healthy dose of map variety, so I´m all for it. Good job.
How about some night time missions? You can have a full moon to have some light on the maps. Also more variety in time of day/ weather forecast would be awesome (fog, overcast, heavy rain, snow etc). Most of the time the maps in Berlin and Normandy are sunny and i think players would love to play them on a rainy cloudy day.