The newer Rome/Medieval II map offers a much better economic model than the old Shogun/Medieval one did, but strategically all it really does is reduce the number of field battles and up the number of sieges. And make it more difficult to move multi-stack armies. It aims for realism, but doesn't have the necessary level of detail for it to really be an improvement.

The Shogun/Medieval map was great because it was basically a board game. Everything was beautifully, elegantly simple and precise. But trade was broken and, since it was abstract, it never felt very realistic.

That being said, Medieval II has left me bored and jaded, and I miss the good ol' days.