Just got Gods & Kings on a whim and...

I like it. Quite a bit. The new civs are fun and the AI is immensely improved, as I feel my attempts at diplomacy actually pay off. Civs actually have a reason to decalre war now. The new customizable religions add a new layer of depth, giving interesting bonuses to the gameplay. Also, espionage is incredibly useful as it's very detail and serves as a new way of interempire dynamics.

I like it. It immensely improves the Civ V experience for me.