They say that the screen will most likely be 3.5"-3.7", but the thinner bezel surrounding it is making it look bigger. Another nugget of info from the news piece is that the back of the phone will be crafted out of metal, not the easy to shatter and heavy glass it has now. The rest of the rumored specs are regurgitated - A5 dual-core processor, 8MP camera and uber-thin design.
If Apple has only upped the screen size to 3.7", or kept the size intact, the next iPhone will look and feel even more minimalistic, as it will be thinner, lighter and with unobtrusive display bezel. The main iPhone competitors lately are flagship Android handsets with massive 4"+ displays, so it will be interesting to see if a large screen has become something to aspire to in the last year or so, or Cupertino has hit the performance/usability sweet spot. Apple has shown numerous times that it can sell successfully with only incremental upgrades, not following trends, but it's hard to go back to a small screen once you've been lured to the dark side.
Analysts have pointed out that Apple is saving its spectacular screen gunpowder and LTE connectivity for the iPhone 6, or whatever the one after the 5th generation is called, so with the next iPhone it might have just aimed to keep the pixel density and resolution closer to current levels, without other bells and whistles, for developers' sake.