The only issue I see in the current beta is because tech speed tends to be faster now, your happiness needs depends on tech level and the needs level of all other civs. You end up researching way faster than you can build so you will slowly slip into a unhappiness hole.
Also, at some point the AI bonuses got shifted. They are very weak early on, but the AI get's a noticeable power spike somewhere in the second or third era. Due to your happiness needs being based on all civs, it can be a sudden happiness issue as soon as the AI's click into "turbo" mode.