Funny how 3.5" was the perfect phone size, until the 4" iphone came out. Despite Jobs' comments that 3.5" was the ideal size, apple were quick with their commercials that 4" was the perfect size when the 5 came out. It's funny to see how they spin things, just like the larger tablet was the only possible size people would want...
As far as I'm concerned, 4" is too small. My current phone has a 4.8" screen, and I'll probably go larger for next.