Its hard to press as in the button doesnt have much give, because of this you have to position your finger directly at the end of it and press down "hard" It's almost impossible to skip volume up and down 1 handed. To do this you need to keep your finger down as a tight grip. You cant repeateldy tap your finger like on most phones.
I tried another one instore today and it was much easier, I then tried the Z3compact and that was even easier and felt like it should. Not sure if its worth emailing amazon for a replacement unit as its only the volume button and likely to wear down.
Was the same thing with my z2, there was just no give with the volume rocker.
I tried the z3 - just slightly better. They got it right with the compact, much better feeling.

