izigame.me

This pack includes one civilization, one district, and the Secret Societies game mode. It is far more game changing than you would expect for a $5 DLC. If you are trying to decide between this or the Maya and Gran Colombia pack then I would recommend choosing this one.
Ethiopia
Ethiopia is the ideal faith civ. They get 15% science and culture from faith output for cities on hills. This bonus stacks very well with the voidsinger's abilities in secret society mode. To top it off they get more faith from international trade routes and an overpowered tile improvement. Seriously, I was able to get 7 faith on one tile with their unique improvement. The game was a breeze on immortal difficulty. My opponents were lagging behind by the medieval era. I don't know whether this was because of the strength of Ethiopia or the abilities of secret society mode. Either way, Ethiopia is a very strong faith civ. One thing that still does bother me is the agenda they decided to go with for Menelik II. He dislikes people who settle near hills. But, hills are over the map. How can you possibly avoid that? I feel like this is going to become one of those annoying agendas.
Secret Societies Game Mode
The Secret Society mode is another optional game mode that changes the way you play the game. Except this one is much more significant than apocalypse mode. There are 4 different societies you can discover and join. You can only join one and once you join one you are stuck with it for the rest of the game. The societies act like empire-wide governors that provide all of your cities with bonuses. I could definitively see myself playing with this game mode for awhile because it boosts various different play styles and gives me a reason to try civs I usually don't play. The societies even affect diplomacy. Civs in a different society than you will like you less and vice versa. Kind of like ideologies. Another interesting thing to note is that when you discover a society it gives you a free governor title. This means you can get governors very early game (which can be really powerful).
Diplomatic Quarter
The first major new district since Rise and Fall. It is like a strange hybrid of diplomacy, espionage, and city-states. It gives you diplomatic favor from embassies and protects nearby districts from spies. It is a one per empire district (like the government plaza). The most game-changing part is its effect on city-states. Many of the city state bonuses have been reworked and now provide some science, culture, faith, etc to the diplomatic quarter along with their usual bonuses to the capital and buildings. This district is ideal for the city-state focused civs (like Greece or Georgia). It also provides more influence points. Without even trying I was able to become the suzerain of almost every city-state in the game by using this district and +2 influence points per turn policy card. The only disappointing part is that they used the same icon for this district as the government plaza. Hard to differentiate between them at a glance without a unique icon.
Conclusion
Now that I'm writing this out I'm starting to realize how overpowered all this new stuff is. Hopefully some of it will get nerfed, but it sure is fun trying them out with some of the older civs. I hope all of the game modes are as all encompassing as Secret Societies.
Additional Notes

The AI seems to have improved slightly, which I hope will continue. But it's hard to tell whether they have become better or are just utilizing the bonuses of secret societies. I've noticed them acting slightly better in regards to religion, but not combat.
Ever since this update I have been spawning very close to other players on every map type i've played. It has led to many unpreventable conflicts (especially when the AI is armed with vampires). This wasn't common for me before the update so I hope whatever change was made will be reverted.