As an old STW player, I used to love battles.

However, Shogun 2 changed the dinamic so much, they've become a chore. I still have to go through 80% of them by myself because I cannot afford losing on Legendary, yet there's little joy to it.
What happens is: maneuvers are simply dead.
Yes, you can change the outcome of a battle a lot if you march for thirty minutes to obtain the best direction of attack prior to engaging in melee. That's actually quite nice.
Yes, you get to outflank the enemy line with a few troops and turn it into a rout.
Yet, the big, pivotal maneuvers during the actual fray are very rare. Three reasons: the first is the least important to be honest, but ya, the AI is smarter; that is good. The second is the absolute ineptitude of cavalry in Shogun 2 -- you could have used a unit or two sometimes, but 90% of the time it won't do you much good, so they're not part of my standard army corps (which goes for eight Katana Samurai, 10 Yari Ashigaru and 1 Bow Ashigaru, plus the general of course, against anything the enemy can throw against me, including couples of stacks of very well experienced all samurai armies; this low cost mix will win it). The third, and the most important, is the speed at which the units die -- by the time I turn a flank, the melee in the center is almost over as well, so the maneuver did not prove crucial anyway.
I tried everything really, I am now playing a Legendary Hojo with Ultra unit sizes -- I hoped that, eventhough it just means more units kill more units, so the difference should be small, it would still have an effect on the speed with which lines of battle tear through each other.
It's just a pity, battles are now simply huge charges decided by timing and Stand and Fight. You'll occasionally envelop somewhere but in that time the other sectors have won or lost their fight aswell sigh.
So ya, I still play the large majority of the battles in single player, but only because I have to.