I started with Hojo on H/H. It went reasonably well at first because kept winning battle after battle but my economy was never strong enough to substain more then one stack and before I knew it I was fighting of a massive alliance from three different fronts and the further I had to withdraw to my original territory, the more factions joined the alliance against me.

So I tried again with Shimazu on H/H, which I'm still playing and it's going much better. After having conquered the island of Kyushu I didn't want expand to my neighbours because I was getting a large portion of my trade income from there. So I decided to cripple my biggest competitors, the alliance of Hojo and Date who together possessed almost half of japan. With a bit a of sneaky diplomacy and a load of cash I managed Hojo to break their alliance with Date, leaving Date so outraged they joined me the moment I declared war on Hojo. I invaded Hojo territory by sea from the north and south coast, however after having conquered around 3 three regions from both the north and south, realm divide suddenly smacked me in the face, the economy went down the drain and my homeland Kyushu was now under threat while my armies were all in in the east.

At the moment I have managed to stabilize my economy to 300 per turn, my homeland is being protected by a strong fleet, hopefully stopping anyone trying to invade, however my army in the east, consisting of three full stacks is having trouble holding on to the tiny bites out of japans backside. I haven't lost any territory yet but I have to chose my battles extremely carefully because losing one battle will cause the enemy to steamroll over me. This is why I love Shogun 2, when this game gets harder it doesn't get frustrating, because when the enemy does something smart it pushes you be smarter and rewards you when you succeed.