1. Craptastic nonexistant AI
2. Combat is kinda boring after awhile, feels extremely unpolished
3. The empire building mechanics are terrible
I haven't played enough to get a good feel for it, but I've found that the AI has been adequate so far, especially the battle AI. I'd agree the combat can be repetitive, but that's a problem with every TBS game I've ever played (Total War series and Heroes of Might and Magic come to mind).
I've seen people bring up the empire building bit a few times, but I feel as though that stems from expectations that the game is about empire building when it never has been a main focus of the series. It's kinda like saying the battles in Crusader Kings are boring.