Although I was absolutely blown away during my first campaign in 3K, I am definitely jaded with it and became so much, much faster than with the Warhammer games.
I think part of the problem is all the factions play pretty much the same, in-battle especially. I know the unit roster was always going to be limited in this title but they don't fully utilise the units they have. Half of them are locked in the reform tree which the AI struggles to navigate meaning you face 90% Ji & archer militia. Additionally, there are no faction-specific effects that alter how one faction might work in battle compared to another with the same units and the differences between the units is so marginal. What's the difference between Sabre Infantry, Axe Band and Jian Swordguard? I couldn't tell you because even after one hard campaign and one legendary one, I haven't needed to know.