The tactical maps make battles a little more unexpected. Only a few have a major effect on tactics (one map has a grove of trees in center, and almost splits your force in half for the starting location, with significant distance between them. This map makes you scramble to re-position!), but they break up the expectations of tactical battles with is a key element of the overall experience.
New stamps are harder to notice (generated a few maps, then played one game), but there seems to be more long mountain ranges, and more thin channels of land bordered by water. In other words, random maps are less like blobs of roughly equal shape, they now have more contour and variety.
Of the two, the tactical probably has more general value. Overall, this DLC made the game a bit fresher so I am glad I bought it.