A lot of the acceptance/rejection is in perspective. Long-term iPhone people can only see these phones and big and "too big". However, the Android crowd who have been exposed to phones with >6" screens can see the 5.5" as "normal" or even a little small and the 4.7" as "too small". Perspective. Even within this very thread you see some whining about "too big" while others are coming back to iOS because Apple finally got the size right (and those are generally referring to the right size as 5.5" model).
Apple has just thrust upon it's fans 2 bigger-screen phones that are well above what was previously spun as a "perfect" size at 4", which itself was a fairly big hop up from what was previously spun as a "perfect" size at 3.5". This is the transition phase, split mostly (IMO) by imaginations that the 5.5" is almost an iPad Mini vs. those who have printed the PDFs, cut them out and thus realized that the differences between the 4.7" and the 5.5" is about 1cm wide and about 2cm tall (in other words, very little difference in physical size).
People are still spinning the pocketability issue (cargo pants, need bigger pockets) and "one-handed use", yet you don't see the Android crowd with 6" phones in specially-made pants or suffering some great disadvantage by involving that spare hand that is pretty much always available to them.
I expect all this whining to continue right into the deliveries and when the stores have the phones on display so that people can correct the imagined sizes with the reality of holding them in their own hands. Then, I expect a lot of this sentiment to evaporate. And, personally, I wouldn't be surprised if the 5.5" sells as well if not better than the 4.7". Again, here- from this group- we're mostly seeing the shock of being accustomed to 4" vs. the bigger 4.7" and HUGE 5.5". But I suspect the reason Apple also built the 5.5" is to draw in those who will find it "normal" or even a little small relative to the phones they own or covet. That crowd will be much bigger than this crowd here. So the sentiment we see here is unlikely to translate well to that crowd or the masses.