...The camera is marginally better, 15% to be exact.
15% is the increase in sensor size. Whatever the resulting increase in pixel size is, the photon capture area is increased by the square of its x-y dimensions (new is 1.5um). I believe Apple's number for both the pixel size and increased aperture (f/2.2 v f/2.4), is something like 33% (an increase of 1/3 f-stop).
Also, the decrease in noise (both in the sensor cell and any decreases in crosstalk) is not linear.
A color temp adaptive flash has never (afaik) been available in a point-and-shoot or other built-ins. The possibilities based on the specs and demo shots look very exciting (if you have to use an on camera flash, you might as well have one that's more on the flattering side).
Add in the new ISP functionalities of the A7, and the upgrade, at least from this photographers view, is substantial, even coming off of the iPhone 5. Some of the noise I looked at in a few of the sky areas in the gallery image(s), looks in the ballpark of my DSL (albeit, it's an aging Canon 10D, though the iPhone lenses would be hard pressed to be in the same league as Canon glass). It took quite a few years to get here, but to me, that makes the effort even more impressive.
I'm still very impressed with my 4s, but I can't wait to pull the trigger early next Friday morning for a 5s..