I came across
this article on Destructoid, which gives a nice overview of what G&K will bring. As usual there's the mention of "better AI"
One change I like is that it's going to be more difficult to gain favor with city states. Now all you have to do is stockpile cash, buy a mercantile cs and turn the excess food into specialists, gain more gold than you spent in the process and then proceed to win on deity. This makes that the whole game just revolves around gold and not much else. With G&K, you'd have to perform some tasks to gain favor with a CS, so perhaps the game will (finally) get an additional layer of strategic depth.
Besides that there will be religion and espionage, which will work similarly to culture. I don't feel this adds strategic depth, just more options. Options are nice, but it doesn't make the game
better.
It might make the game more entertaining though, and that's what civ5 is: entertainment. That's definately not a bad thing, and I think it's a pity not more of you give this game a chance.