I noticed that when using reachability my home button on my 6 Plus sounds hollow. I at first thought it was loose (maybe it is) so tried to move it around, but it doesn't, but when tapping with reacabiltiy it sounds really hollow? Kind of cheap sounding and feeling. Just wondering if this is normal? I compared to iPhones in the store by couldn't really hear. Some of those did move from side to side though.
Mine clicks sometimes and on other occasions it's rather tactile. I would never say that it sounded hollow but these are mass-produced items and there will be differences between phones. Then again, I never use reachability so don't tap my home button.
Having just received a replacement phone I can say the home buttons do vary. My home button now clicks rather loudly vs. my old one I had a technique were i could press it without a clicking sound. But i agree with the others that if the phone works a clicking or hollow sound isn't a big deal.