I'll chime in. I, too, have been mainlining, er, "playing" Civ since the first version. It's been my principle form of entertainment for more than 20 years now.
I think Civ VI is the best out-of-the-gate version I've ever seen from the series. It's got tons of systems and lots of interesting ways to play the game.
Unfortunately, it retains the worst mistakes of CiV, which makes it very tedious to play in the late game. In some respects, this has been a problem for the series all along. I'm talking about unit movement in the late game. When you have huge armies and you need to engage against a player halfway around the world on a huge map, then your army is going to be a few tech generations behind by the time if reaches the theater of operations. It's a huge problem that they've never figured out how to deal with--I don't even know they're trying. Movements speeds just need to be significantly ramped up for the modern era, but they can't seem to reconcile that with turn-based combat. When they shifted to 1upt, though, things got really ugly and moving an army is such a chore that in CiV, I refused to wage war until I got those Xcom units that I could actually pop across the globe in a blink. Anything else was too frustrating as I'd set a unit destination, then have to reset it the next turn because some worker happened to stop and block the tile my unit wouldn't arrive in for twelve turns anyway, then two turns later I'd have the unit blinking at me and forget where the heck it was going.
Now, for me as an unrepentant wonder whore, I'm also not crazy about unstacking the cities. It does add a whole new layer of strategy to the game, yes, but it also stretches the conceit whereby a city lords over such a huge swatch of territory on the map. If this game is super moldable, then I'd love to see all this unstacked city mechanic get pulled back into the city. Like, what if there was a city view again like in the good old days, but it was a fat hex tucked inside your city's hex? Then you could place your buildings and they would take up more reasonable amount of space in the game world--instead of, say, the Eiffel tower requiring five hundred square miles. If this mechanic was workable, then you could even have the option for tactical combat. Up to three units on each side could enter a zoomed-in fat hex from opposite sides and you could use terrain advantages more logically--so again, archers wouldn't then be firing across the English channel and such.
Just a pipe dream, I know. But my point is: Civ VI is pretty good, but as always, we dream the game we want to play and sometimes the reality is disappointing by comparison.