I played AOE 1, 2, 3. I find AOE4 to be a traumatized child of previous 3 installments. They spent more time in environment, buildings and cues like language that identifies civilization. Units are not impressive, all units look same in civilizations, In AOE3 it was much better, sepoys for Indians, red coats for British, mercenary post to hire foreign units etc. In AOE4 wherever I turn spearmen, archers, man at arms and horsemen they all look same, nothing specific to civilization in terms of look, feel and behaviour.
Second point which I would like to share is, ages in AOE4 will reach early gunpowder age where you can recruit early gunpowder men and weird artillery example four cannon artillery at age 4. This does not give a feel that we are in a higher age.
Campaign is playable, but you have to keep in mind that only few civilizations make it to main campaign. The narration style mission start is creative.
Last point I would like to point out is AIs, if you play a skirmish in map with rivers where we have to carry troops to other side for attacking, AI especially the allies are sloppy, they do nothing except killing off gold mines and other resources, they don't attack, they don't patrol the enemy territory, we just have to win by building a wonder or attacking all enemies by ourselves.
Overall, feel good though, less impressive and heavy tech abomination