Since upgrading from an iPhone 3GS/iPad 3 to an iPhone 5s/iPad mini Retina, something that gets on my nerves is the separated volume buttons.
IIRC, Giz pointed out that the buttons are now separated with the iPhone 4 when it was released, and either they were simply pointing it out, or they also mentioned that it's 'better'.
If the latter, I disagree, I can't see how it's better; too many times have I tried to turn the volume up and I've accidentally turned it down. Why? Because both the buttons are exactly the same. If it was one strip, then I just need to feel the edge of the button to know if I've got my finger on the up button or down button.
I guess people need to get used to it or something, I think it's a bit of a dumb idea to make the buttons exactly the same. I think it's also supposed to be 'cheaper' to just use one piece of metal for both buttons, but I don't know why anyone would care about how expensive their volume button is...
For reference, here's the iPhone 3GS.
Note how it gets taller where the actual button is, that helps even further to distinguish the two.