I started a game of Rise and Fall over the weekend, but haven't gotten very far, around turn 250 of a 750-turn game. One thing I remember reading from a developer was that they wanted to juice up the late game, which it desperately needed. I haven't played the last 1/3rd of a game of Civ in a year. So far, the new systems haven't tremendously improved the game for me, but I'm going to see it through to the end and see if the late-game has been improved.
The "Loyalty" system: So far, it's done nothing for me. However, a friend theorized that Loyalty might dissuade the AI from founding cities all over creation, and maintain its national borders better than it used to. In the early stages of my game, I haven't seen the AI flinging Settlers hither and yon, so maybe he was right.
"Era Score" and Dark, Golden and Heroic Ages: I seemed to acquire enough Era Points just by doing what I normally do. I had one Golden Age, which didn't seem to do much. It improves your cities' Loyalty, but that had no effect on my game, as it was. I chose a +10% bonus to Eurekas as my Golden Age bonus, but they reduced the normal Eureka bonus from 50% to 40%. I think the menu of Golden Age bonuses you can select changes with the Era, so maybe later Golden Ages have more impact. I haven't experienced a Dark or Heroic Age yet. I saw one of the AIs suffer a Dark Age while his neighbor had a Golden Age, and two cities on the border flipped allegiances.
The new civs, leaders, Natural Wonders and World Wonders seem cool, but not game-changing. I'm playing Poundmaker of the Cree. I haven't built any of the new Districts or used any of the new units yet.
I still crushed the AI like empty soda cans in wars, though. The AI still doesn't really put up a fight. It remains to be seen whether the new systems will balance things in favor of the AI, but fighting a war against them is still basically an exploit.
I got one "Emergency", which seemed a little overpowered. Korea took a City-State, and then didn't defend it. I liberated it easily and was showered with Gold in addition to getting the CS bonus for Suzerainty for a while. The latter has always been the reward for liberating a captured City-State, and this new "Emergency" system only makes it more lucrative, which the human player really didn't need. But maybe this "Emergencies" system is something that really blooms in the late game.
The City Governors seem cool, giving you some more levers to pull and moving them around to best utilize their bonuses gives you something else to think about.