I really like the character cards that pop up when you mouse over a hero, but the game will not pop up the card when you mouse over the currently selected unit.  I'm not sure why not, I think it'd be really useful to be able to see the card info for the selected unit.

One place I really wish that worked is when I'm considering recruiting a hero: after I select the hero to see if I can recruit him/her, I often want to double-check the stats. ("Does this guy give one or two research?")   I can press the Details button for the big window, but I hate the character details window and just want the quick card info.  The game won't show it because the hero is selected, so if I want to see the character card, I have to deselect the unit and then do the mouseover, then reselect the unit and recruit it.