Maya Civ: One of my personal favorite civs. The focus on organizing cities within six tiles and the prioritization of farms and luxury adjacencies over fresh water make for a highly distinct play style.
Ethiopia and Gran Columbia Civs: While the Maya are my favorite of the pass so far, more civs are always welcome, and I'd rate both of these in at least the top half of the game's civs with regard to providing distinctive gameplay.
Catherine and Teddy Persona Packs: I would have preferred this effort to go into actual new civs, but Bull Moose Teddy's new ability is definitely fun, albeit probably overpowered.
New City States: Another great way of bringing game to game variety. I've particularly enjoyed Caguana and Vatican City, and while I haven't yet gotten to make good use of Lahore, the idea of a city state based UU is really interesting.
Diplomatic Quarter: A simple but effective district addition. I do think it was a mistake to put this in an individual civ pack, though, as this makes it much more difficult for it to interact with future wonders and other game elements.
Apocalypse Mode: Some fun ideas, but they don't really fit together very well. Why are civilization ending asteroid impacts triggered by CO2 emissions? Why are their effects so localized? The soothsayers do add some interesting gameplay, but there's no way of using them without this extra weirdness.
Secret Societies Mode: This adds a lot of potential for unique strategies and interactions. It's far too over the top and fantastical for me to want it as part of my normal setup, but its well worth playing when I want to shake things up.
What does this add up to in terms of the pack overall? Really that's a question of what your baseline for comparison is. Personally, I've been thinking of this as a series of civ packs like those between vanilla and Rise and Fall. By that standard, the new civs and the small main game additions are great, and anything beyond that is just an added bonus. In contrast, for someone who needs an expansion's worth of content to justify the pack's price I could definitely imagine coming away disappointed.