Im a maxis iphone user, been using it for 185 days (i make a note in d note apps right afta i got my iphin ).
atm, i felt tat d home bttn is pretty sunked in. But, if you ought to look at its mechanic, it will likely reacts wen u pressed right in d centre of d button. few weeks afta i got my iphin, i spammed d home button n notice d responds time is somewhat slower from 'main page' to 'search' afta few times. I assume slow response is not just related to d sensitivity of d button but also d processing part.
Thus, my point is as everyone else would said, test everything, i mean everything on ur iphin within a week of ur purchased. d sooner d better. Warranty, satisfactory nowadays isnt as simple as it used to be. just my 2cents.