It's both actually! It's one centralised AI for everything, which means it can learn pretty easily. We've been more focused on other stuff at the moment though, which is why the AI isn't improving a lot at the moment.
We'll be hard at work in the future to not only make the AI loads better but to also offer an offline version! We understand not everyone likes the idea of the game being online all the time, even if all the information is completely anonymous.