The entire series is good honestly.
However with 6 the changes in some aspects are mixed. The Civs seem more unique. The art is wonderful.
My main issue is with the district system for the cities. I understand it even think it is a good idea. One that I have thought about since civ3. The execution of it is greatly lacking. There is no reason for so many tiles to be used in such a way. They could have broken down the tiles so each tile is 2 or 4 districts. Building time in this game is ridiculous. You don't get enough production for what you have to do.
It gets points for innovation however this system needs cleaned up. As well as the housing portion of it.....
If you like the series yes get it. If it's you first time I suggest 5 or 3. Or maybe not cause then you won't have something to compare too.