Clarity change: Segmented minion health bar
Their health changes during the game, so it's a bit difficult to determine how much current health they have exactly, unless you select them, but you can't left click before every Last Hit.
So you'll have to wait for the last possible moment even though you'd have been able to hit earlier. This is especially frustrating for execute type abbilities like Nasus or Veigar have.
Champion health (segmentation) and large monster health (actual number) is much clearer. I'd like to see something like this for minions and small monsters too.