I've used in the last few years
3", 3.5", 4", 4.2", 4.7", 5" and a 5.7" phones. From Blackberries, to iphones to samsungs to the Nexus.
the only thing I learned....
it's purely subjective. Everyone has a different idea of what the perfect phone size for them is. There's no one rule to rule them all. it is clear by the sales of larger phones that there is a clear market for devices over 4". to claim otherwise, or to believe that somehow 4" is the only good number is silly.
The made up excuses some of you use to claim why anything larger than 4" is stupid, going so far as to actually insult people not using iphones 4" screen is pretty sad and reeks of fanboy. is it so hard to say "that phone size doesn't work for me". Instead its "anyone using a big phone just likes bulges in their pockets!" or "idiots who need large phones". come on. Get off it.
Personally, I found anything less than 4.2" reminded me more of the early days of PDA's and "dumb phones". Yes, they are full smart phones, but with the smaller screen, I just felt cramped.
On the flip side. I loved my Note II's large screen for some things, but overall I felt it was too large for comfortable usage for my "small" hands. Dont get me wrong, The note II fit perfectly fine in my pants pockets. And no, they're not "low baller" pants. or "baggy jeans". they're normal everyday work dress pants and my everyday regular fit jeans.
I'm now using a 5" Nexus 5 and it feels like such a relief from the note II sizewise. No more hand cramping as I try to one hand operate it by twisting my hand at uncomfortable angles. however, I know lots of people who are happy with their Note II's size and can comfortably use it.