My biggest beef is when a moving unit spots a static unit that has opfire shots available at close range but the moving unit still gets to shoot first, sometimes multiple times. I do not know how the game calculates when a unit spots another, but I think in most cases that the static unit would have...

The opfire thing has had me miffed on a number of instances as well. I can't count the number of times that I've placed a tank in a position hidden from an enemy armor unit's view (around the corner of a hedge, for example) knowing that the enemy unit would not be able to spot me until it has moved ...