Transferring money in diplomacy now has a stronger effect on the AI, but the AI is much less willing to give you money.
When making a diplomatic offer, the AI will check if it's willing to give you some money along with it, and automatically add the money. So you no longer have to edit each diplomatic offer to make sure you get that extra bit of money.
If your reputation is very low, the AI is less interested in getting tribute from you, as it doesn't believe you'll honour the deal. The same applies to a lesser degree to trade and research treaties.
You can now save medal designs in a persistent medal library:
You can now set the map generation seed in single and multiplayer conquest games. Newly created games now also show in the settings tab what seed was used. This means that if you find a nice-looking map, you can reuse it. Make sure to use the same settings for map size, land coverage, monsters, etc.
Finally: Bees, aerial dragoons, and other flying boarders will now pick a new target to board when their original target is no longer available. And the moon disk now takes less damage from ramming but has fewer HP overall.