It would be nice if overwatch didn't sometimes fail to trigger, when it clearly should.
Likewise, it would be nice if, when one enemy triggers multiple overwatch, the enemy stayed where it triggered the units, or all triggering units fired the instant they are triggered without each getting a cutscene.
The number of times I have watched one unit trigger properly, then the next unit shoot after the enemy is 80% out of the triggering window and all units triggering after this shoot into the wall where the enemy now is because the enemy continues to move while each previous shot is taken, but only one shot at a time can be shown is disheartening.