I fly AA F/J class and use "the button" when I want something like a snack or drink. I usually know what I want (a glass of the pinot noir... a banana... more nuts...) and am polite and businesslike. I don't think I've ever had any reaction that was less than the same back. Worst case, it can take some time if they're busy with something (blocking the flight deck so the pilot can pee, etc).