Less micro management: One of the hassles of the Total War series since Rome (which introduced the concept of tile-by-tile moving units on the campaign map instead of the province-to-province, Risc style of Shogun and Medieval 1) was the many single-unit armies you were commanding: In order to get reinforcements to the front, you had to send them there. And although you could just tell them their target spot and wait until they reached it, they still cluttered the map. Empire Total War will have a different approach: Here, generals are calling for reinforcements, and they will be sent to them automatically from their home cities. You'll be able to see that reinforcements on the map, but in a way which makes clear that they are no active units, yet. In order to get reinforcements to your field armies, they need to be "land linked" to at least one of your cities. So after a naval landing, without securing a town on the same isle or continent, you won't get those reinforcements. By this new system, Creative Assembly wants to ensure that there are less playing pieces (Armies) on the campaign map, but each being meaningful. It will be still possible to split your armies, though.
Oh Joy! Does this mean the end of all those annoying battles against 1,2 or 3 enemy units? Soooo tedious and a waste of time - but you can't autoresolve them because of the high losses your 12 unit stack suffers. I'm only interested in the proper battles