Did a quick game on King to get a feel for the version. Communitas, default settings. I did play as Khmer for Vox Populi, who I think are a little overtuned. They made the Tourism victory too easy, but they were not my main problems with the patch. Firstly, the AI is just too passive. Once I got diplomatic vision of the other continent, I could see Atilla with a massive army neglecting to kill Ethiopia despite being easily able to. Rome attacked me several times, concluding with me taking two of his cities, one of them his capital. I annexed Rome and puppeted Cumae - I had settled 4 cities myself this game. Later I puppeted a Carthaginian city. I faced zero happiness issues the entire game, and happiness was in fact a non-issue despite growing all my cities as hard as possible. I feel the new system is far too generous and basically defeats the point of happiness altogether.
As I was pushing my tourism to dominate everyone, all the AI, even neighbouring Incas with military superiority, happily traded with me. Open borders, favorable deals, everything. The turn before I became influential over him, Pachahuti gave me a luxury resource for free. The AI would continue to raise no resistance to my cultural domination - I only ever got in one war after I conquered Rome, which was Atilla declaring war on Rome to take some of his terrible one-tile island cities. After this he ended up peacing out with me, not trying an invasion, the turn before I completed Citizen Earth. Rome was able to declare independence for the last 50-60 turns of the game, and had a reasonably strong army to do so with - if they had pushed their advantage, it would have slowed me down. Similarly, the Incas were always in a position they could attack from, being largely technologicaly matched and their army outsizing mine. But nothing ever happened. No-one tried to stop my victory - they didn't even try to embargo me, or stop giving me open borders. King may not be intended to be a herculean challenge to beat, but I do think it used to be much harder a year or two ago. That may be my rose-tinted glasses speaking, but I distinctly remember being barred by nukes by warmongers the moment I started threatening a victory.
The new happiness system, despite being too lenient, is still a fantastic upgrade that's so superior to the old one it's amazing. Fantastic update, just needs to be a little more rough. Difficulty 5 is supposed to correspond to 6 or 7 in vanilla, but the AI just didn't put up a fight whatsoever. Bring on the AI agressiveness!