It's funny how all the people with iPhones say that 3.5" is perfect and anything over 4" is ridiculous, while everyone with a larger phone agrees that 3.5" is just too small. Could it be that you don't really know how you would like a larger screen until you've tried using one for a while?
I know I thought a phone with a 4.5"+ screen would be ridiculously large back when I had one with a 3.5" screen. That screen size felt just right for me at the time. Then I got drunk at a bar one night and lost my phone (yeah, that was stupid, but at least it was a cheapo ZTE phone), so I had to get a new one. Decided to get the Galaxy Nexus, with its comparatively massive 4.65" screen. At first it did feel larger than I was used to, of course, but I quickly adapted and very soon it didn't seem very large at all. Now I wouldn't want anything smaller than 4.5" or so.
So, the point is this: To those of you saying 3.5" is perfect and anything around 4.5" is ridiculous - maybe you wouldn't feel that way if you tried living with one for a while. Of course there will be exceptions - for some people 3.5" probably is perfect - but most people who have gone from something smaller to something larger (at first feeling a bit hesitant) seem to share my feelings about it and agree that going back to 3.5" would feel very tiny and cramped.