edit: And now that I've written this massive wall of text, they've released a patch for the game addressing some of these issues. Not all of them are fixed, however.
https://forums.2k.com/showthread.ph...e-Now-Live&s=b6ffe960ca2f79fc959edb6869fd5cb9
Incoming all of text.
I've been playing for a few dozen hours so far, and the game definitely has some outstanding flaws. Namely, the UI and AI are (nearly) completely borked.
The UI is terribly designed. Especially when compared to other Civ games, which are usually are very innovating in this area. This makes the game sluggish because every action takes just that much longer to do and is just that much more frustrating because you have to perform that action through a p*ss poor UI.
The AI is pretty terrible as well. Particularly when it comes to diplomacy. I just don't get 90% of the things AI leaders do... Insulting you for something on one turn. Praising you for the exact same thing 10 turns later.
There also seems to be no standard cost associated with resource trading. In the early game, leaders offered me 5 gold per turn for each luxury resource. In the mid-game, Egypt kept offering me 1 GPT (a single GPT) for a THREE ! luxury resources. In the late game, and France kept offering me "trades" where I give them three luxury resources and open borders for nothing. That's right, LITERALLY NOTHING. This was especially odd considering France denounced me. So it's not like we were allies or anything.
Another example of how bad the AI are leader agendas. Agendas are probably the worst feature ever added to a Civ game. Agendas turn every leader into an ideologue who hates everyone who doesn't fit their obtuse criteria for friendship. Rome is a rapid-expanding Civ that dislikes everyone who is smaller than them (so basically everyone). America declares war on anyone who declares war one anyone else, and refuses to make peace for the rest of the game. Kongo dislikes anyone who doesn't spread their religion to Kongo's cities. In one of my game, Kongo literally kept denouncing me for not spreading my religion to them even though Kongo was literally the farthest civilization away from me. In summary, leader agendas are completely absurd and completely break the diplomatic game in some cases.
A few other annoyances....
The conversion rate for merging units is abysmal. In most cases, merging two units creates a new unit that is only 20% more powerful than one unit of the same type. Oddly enough, adding a third unit is even worse. Adding a third unit only increases by 10% of just one unit. So merging three units creates a new unit that is only 30% more powerful than just one of that unit of that type. It is utterly ridiculous and completely non-sensical. None to mention, the ability to merge units is unlocked too late in the game to help reduce micromanagement anyways.
The new "Casus Belli" system is badly implemented. Unfortunately, you don't unlock any Casus Belis until the Renaissance, and they are all unlocked by the same technology. The circumstances in which Casus Belies can be used are extremely restrictive. So you can expect to get the full Warmonger penalties for waging war in 90% of circumstances. For instance, you can only declare "Holy Wars" if you ask a civilization to stop spreading their religion to your cities, but they keep doing it. Say goodbye to waging Holy Wars in the Middle Ages! They are not the feature I expected.
Other than that, most of the new features are good. City planning is good. Most of the features from Civ V are improved in Civ VI. But this also creates a small problem where there is now much more to do and it becomes overwhelming. This is exacerbated by the p*ss poor UI.
Overall though, Civ VI is definitely an improvement over its predecessors. But it badly needs a patch to fix the UI and AI. And possibly even a mod to fix some of the things designers might refuse to fix. If you haven't already picked this up, then I would recommend waiting until they release a major patch.