You might register the little differences this pack provides at first, but after some few hours it becomes pretty much irrelevant. Only for enthusiasts.

A not existential but very recommended expansion. The council enriches the gameplay within your empire in multiple ways. It allows your vassals to compete for power but it also gives you a better option to shape and organize your realm. So even if you are big enough not to worry about external enemies, the internal competition keeps the campaign entertaining.