In Age of Mythology you can select any unit or building and right click on their icon to get a incredibly handy page with all the units’s stats, what counters and what is countered by, what upgrades it has and what is their exact effect on the unit and a nice a text on the unit’s historical context.
While AoEIII is much more straight-forward with it’s unit stats than AoM, it lacks a page where you can get quickly get a full breakdown of the units. The game’s compendium can’t be accessed during a game, and doesn’t list stats anyway, and the game UI can’t show all information at once. And there is no practical way to tell which upgrades are currently in effect for each unit, and how much they are actually helping. Obviously such a feature will be a god-sent for new players who can often get lost with AoEIII’s big roster of units and counters. For me, having a easy way to check upgrades will make my life a lot easier as I try to compile data for things like The Revolutions Guide.