After playing this game for a considerable amount of time (many offline hours not counted) here is my opinion.

Pros~
~The District System is Very Neat and I think it is a Wonderful Addition to civ. It allows much more diversity when planning how to plan your cities.
~New Policy system is quite unique and fresh. That being said I would love to see the indrodution of having to choose negative policies. (your Government can be all positive ya know)
~less reliance on building wonders (Civ 5 you pretty much win the game if you could build the wonders before your opponents)
~City states have been greatly updated since civ 5 (all kinds of unique and cool bonuses)
~improved multiplayer. (Way better then Civ 5)
~Great people now have new system which is really cool


Cons~
~ AI is terrible. Prob the worst AI I have ever seen. Not only are the AI absolutely terrible at combat but they often impossible to please. ie. most every game i have played result in every nation being Angry at me even when i have never declared war.
+note on AI in all the games i played it was clear that some of the AI Leaders have clear Advantages over the other AI leaders. For example Germany was almost Always at the top, and Egypt at the bottom of the score board.
+ note AI has been receving updates and may improve in the future.
~ Religion Has not changed at all since Civ 5 . (the Ai also spams missionaries and apostles and blankets your map with them, this can be really irritating)
~ Personally I did not like the art direction, after Civ 5 i was hoping that the developers would pursue a more realistic aproach to the the next game. The leaders look extreamly goofy in my opinion.
~ No Dlipomatic victory yet ( There is now a Religion victory)
~ Diplomacy with AI is Pretty Bad
~ Alliances with AI are pointless ( if you get attacked you ally will never come to help you)

I could go on but, these are the main points I feel should be brought up. I want to say i was really torn on to give a positive or a negative review. there are lots of things that i liked but there are also things that i wish that could be undone. If you are a Civ fan I can't really say if you will like it or not, it has it's weaknesses and strengths. I would say if its on sale buy it but, at its current price its not worth it. Hopefully the DLC will spice things up in the future.

~Locomotohobo