You know to tell you the truth, I don't really pay attention to the visual changes made to the game, if I do it's probably because it was irritating at that time or just noticable. I remember joining literally right before they removed the health bar that existed below-center of the screen in mid-2014. I also remember how shitty the chat bubbles were sometime in mid-2015 because they made them translucent, so it was harder to make out what people were saying, especially if one chat bubble was overlayed on top another chat bubble from another user, because those two users were standing in proximity of one another.
There was also a third thing I was going to mention but I forgot.