Instead of adding the few lacking features that held Civ 5 from being perfect, they for some reason decided to build a completely new game and fix what wasn't broken. A lot of the changes are not exactly objectively bad, but I suppose it's a matter of preference, and I prefer Civ 5.

Top 3 things I disliked the most:

1. Policy system.
2. Movement point distribution.
3. Interface/visuals (I'm okay with the cartooniness, even though I think Civ 5 achieved a perfect blend between realism and vibrancy, but I really hate the new FOW, and I found the interface less intuitive than in 5).

One thing I really enjoyed was the disasters and dynamic landscapes. Aside from that, there's a lot of nice little things that I wish they'd just built on the Civ 5 foundation.

Overall, not a bad game, but really pales in comparison to its predecessor. And weighs 33 gigs, against the 8 of Civ 5. I could commit more hours to it, but because of the weight it really doesn't feel worth it.

P.S. Wtf happened to music? The music was amazing in Civ 5 and adaptive to whichever culture you played. Here it's so minimal and basic, and plays random compositions. Totally kills the mood.