i think i can speak to this as i went through a pair of defective PW2s (and also having owned two refurbished PW2s) which eventually led Amazon to send me a PW3 (long story)
my detailed review is here on Amazon:
http://www.amazon.com/gp/customer-re...SIN=B00QJE3MGU
but in summary and now having lived with PW3 beyond that review, i'd say:
- without comparing them side by side, i felt initially, there was no huge improvement with the PW3
- yet, when comparing them side by side, it was evident that the font on the PW3 is cleaner and appears to be "lighter in weight" regardless of the font chosen. i am guessing this is what some people view as lighter contrast and some people actually prefer the PW2.
- finally (what is not in that review posted above): just the other night, i picked up my wife's PW2 and was immediately struck by the lower resolution compared to my PW3, even though i wasn't comparing them side by side. it's not that her PW2 looked bad, but it just didn't have the crispness that i had grown familiar with and accustomed to with my PW3. i think initially, it would be hard to go back to a PW2, now that i've used my PW3 for a couple of weeks.
for someone on the fence, i think it's hard call. i can see how someone might prefer the PW2 due to the "thicker" looking font which may come off as "blacker." but for me, i'd prefer a better defined cleaner font, even if the font weight appears lighter.
the only thing that i think is truly in favor of the PW2 and may matter to some is the extra 25% battery life. the PW3 is no slouch, but the fact remains that it has a 21 hour vs 28 hour specified battery life (me extrapolating the Amazon 8 vs 6 week spec at 0.5 hours a day).
Caveat: i have never had the pleasure of looking at Voyage, but from what i understand, there appears to be a higher contrast with the fonts due to the different screen. that would make sense given my experience with the later generation iPhones having more of a "pop" as the screen has gotten closer and closer to the front glass.
ps PW1. i've borrowed a friends which actually had a reasonable backlight (not too shadowy and nothing i noticed -- i am less picky when someone is loaning me something as opposed to me spending my own cash to own an item
). i don't think there is a huge perceivable difference between the PW1 and PW2 except perhaps a more uniform backlight.