Dog knows I've posted plenty of complaints about how Civ VI does things, either in comparison to other games or in comparison to the history it purports to be loosely based on but isn't. And some of the complaints about Firaxis' apparent inabilty to fix bugs or get systems to work together or even notice massive Imbalances in game play and the leaders and civs themselves deserves to be pointed out, loudly and repeatedly.
BUT Between Civ V and VI I've put in almost 10,000 hours playing the Civ games (I don't have the hour figures for the time I put into Civs II, III, and IV, but I suspect it at least equals the time spent on the last two games, which is a little disturbing, to be frank) so either they are doing something right or I'm a flaming Idiot (don't nobody comment on that, thankyouverymuch).
Mind you, the tenor of my complaints might be a little different from most, because I have never been very interested in winning the game as much as in playing the game. I could care less about 'paths to victory' or people complaining that "X Civ is broken because you can always win by doing YZW with it." - then don't do YZW: problem solved (at least for me).
Does the game have a 'good' AI? Define your terms. An AI that can consistently beat most Human Players is A: Not much fun to play against, and B: probably not possible given the current state of AI in general, at least not in a game budget (and, given the little problems they are having just getting an AI to move a vehicle from Point A to Point B without running over curbs, people, animals, other vehicles, I suspect we are a long way from getting an in-game available AI that can do human-type path-finding over a 15,000 tile map).
Is the game balanced? Not by a long shot, but for the most part the Imbalance is in the Civs and Leaders. Then you don't play with those Civs and Leaders, and let the designers know that they've wasted a lot of time and money putting together Civs and Leaders that will Never See The Light of Day.
Is the game Fun To Play. That's an individual question, with a different answer from every single gamer, and probably a different answer from the same gamer at different moments. But, this is the most fundamental question, as long as we are talking about a recreational game and not a masochistic exercise. And even here, for almost everybody the Fun part is in different aspects of the game, and in anything with as many components as a 4x game, some parts are Funner than others, and in the end you balance the parts you enjoy in the game versus the parts that make you want to heave your computer out the nearest window (which, since I play on a large desktop machine, takes real effort, but at times it has been close . . . )
So far, Civ VI is still Fun to Play. For me. Some of the time. I submit that that is the best any game company can legitimately expect and the best we can expect from any game company.
That doesn't exempt the company from being beaten like the proverbial rug in these forums for things in the game we don't like, but Get Real: the only way I or anyone else will get a game we are 100% satisfied with is if we design, program, finance, test, and then play the game entirely by and for our individual selves. Unfortunately, I left my several million dollars and years of programming experience in game software in my other pants, so I'll keep harassing Firaxis with suggestions to bend the game in the direction I'd like to play it.