After so many years, I finally got this (free on Epic), and as a veteran Civ player (since the first on the amiga), first impressions weren't good but the game is growing on me.
My biggest peeve is the lack of flavour. Even a small menu on Civ 5 had more flair than Civ 6. The wonders paintings in 5 were much more effective, and some of the quotes in VI are frankly ridiculous. They even included that bullshit story about NASA siphoning loads of dollars into developing a space pen, and the Russians taking a pencil, when everyone already knows it's bullshit. Also, quotes by Ayn Rand? Seriously? It was obvious that Civ 5 was made by much more cultured people.
The Civ choices were also ridiculous, but enough has been said about this. Diversity is nice, but colonial european civilizations is stupid. Brazil? Australia? Grand Colombia? Canada? Instead of Portugal? I can accept Americans because they won the real world game of Civilization.
On the other hand, I like the districts, and it will hard to go back to V because of it.
AI is worse, and in the last game I captured 4 barbarian settlers....no shit. And the AI leaders lack aggressiveness, but that was already the case in V with the expansions.
There's barely any penalty to ICS. The only that I noticed is that luxury resources only feed into 4 cities, so in the long run cities will start to lose productivity, but isn't enough. Civ 5 went to far into penalising wide empires, but this is too little.
Not entirely convinced about the Civics/governments. In 5 it wasn't perfect because it forced us into a path very early, but now it's about choosing between similar civis with some modifiers. A bit more micromanagement for very little reward. The system in Endless Space 2 is the best, and I hope Civ 7 copies it.