Ok started a new game in 2.4 version and i noticed that the AI has some new interesting strategies. For instance before he would attack at the same spot onto my defense line without too much toughts on his casualties. Now he tries to go around and if that fails he simply builds his own defense lines (keeps his units in bordering cities) and waits for my move. This led in my case that the AI had heavily defended cities with 20 or more units which is not so easy to conquer. And if the AI notices that i removed some of my defense lines he quickly goes into a counterattack.
Also he finally keeps some units in his less threatened cities so making a diversion into deep AI territory and capturing cities is not so easy as before. All in all congrats to the devs as the AI is now much more challenging than before.
The only drawback I noticed is that the AI forgets to build buildings other than barracks and city walls. It would be good that he has some better developed cities.
Some notes about the AI improvements in 2.4
Re: Some notes about the AI improvements in 2.4
The AI seems to play smallpox...lots of 4-6 size cities, close together (maybe I should fiddle with mincitydist), churning out units en masse. Whichever one grows fastest first, wins, all else being equal.