The AI has noticeably improved in terms of city and district placement, religious belief choices, city state suzerainty, and defensive combat, but still doesn't effectively wage offensive wars or target victory conditions. After you get past turn 50 or so on standard speed, you're still not going to face any real risk of losing and any fun you get out of the game is just going to come from optimizing your own play.
If you want a real challenge from the Deity AI, though, try an online speed game. The AI is much more aggressive on online speed and can just constantly crank out units. They won't take your initial delegations and, if your military is smaller than your neighbors (which it almost certainly will be), they will declare war. It's a real challenge to fend them off while still keeping up in development. The AI's bonuses are magnified while your human advantage in planning, maneuvering units, micro-managing tiles, and chopping is minimized. Handpick some good opponents as well, to create military threats in the early game and at least some competition on each of the victory paths for the mid-to-late game--I suggest some combination of Korea, Australia, Macedon, Nubia, Russia, America, China, Rome, and Pericles Greece.
