The fact that Samurai require Iron only. They can't even build regular Macemen if you don't have iron then, which absolutely blows. And if Toku wasn't crap enough already. :/
Also, the "worst enemy" nonesense seems to be just another way of penalizing the player. Being a worst enemy doesn't mean they'll attack their worst enemy, but it does give them the excuse to give you penalties for trading with them and suddenly you're they're worst enemy (even when they didn't know you were!)
It's most hilarious in a continents game, some guy comes over and hates the people for some reason and you get a -4 automatically. Because clearly that is worse than declaring war on them, nuking them, or razing their cities.
The worst was some random game yesterday when Shaka was across the continent, and hated Brennus. Yet he still goes attack me in the BCs and bribes Qin on it too? Lawl wut. And the worst part was that their armies weren't strong enough to do anything except pillage my mine and suicide into the city guarded by 3 archers, 2 axeman, and a wall. Once I bribed Brennus into this, I never saw any more units from Shaka; until I bend Qin over with Cav and Qin peacevassals to Shaka. Of course! And Shaka gets owned too. All for nothing except giving me great generals and slowing down my tech pace while the other continent trades like hurr hurr.
But oh wait, I have a great ally with Brennus right? After all +5 for mutual struggle, +6 for religion, +3 for civics. + for trade relations and resources, and I forgot how many for giving them help. We're best friends right? He's sure friendly and greets me well. Wait, why won't he sign a defensive pact? Oh wait, he hates my vassals. I forgot. I enslaved our former enemies, and he now hates me for that.... but he'd rather just lie about it.
So anyhow, I somehow win a diplomatic victory because it's between me and brennus, and the other people who are mildly pleased with me vote me in. Actually I didn't even know why they voted for me, maybe they liked my vassals?
Although it's kinda hilarious if you think about it. The best way to get people's votes is to conquer their best friends. Right... It's only a -2 for declaring on them after all right? Better that then to get owned by averaging.
I win a diplo victory where my best friend probably wouldn't vote for me even if he wasn't eligible. Anyhow, that was really a game where everything ******** with the game really did happen. I think I need a break from Civ.
It's really kinda sad such a good game can be ruined by trash features like this. There should be options to only allow vassals through capitulation, disable only the AP OR UN, and such....