The original iPhone camera was nothing to write home about. Even at the time of its release, photo quality on the original iPhone lagged behind a number of competing smartphones. Today, the story is much different. Today, photo quality on the iPhone is arguably best in class and Apple, understandably so, loves talking about it. They even made a commercial about it.
During every iPhone unveiling, it's a safe bet that Phil Schiller well spend a good deal of time talking about all of the great new picture quality and engineering enhancements Apple managed to bake into the latest and greatest iPhone.
Looking ahead to the iPhone 6s (assuming Apple keeps its iPhone nomenclature intact), Apple may have few camera tricks up its sleeve.
During the most recent episode of John Gruber's podcast, "The Talk Show", the well-connected Gruber passed along an interesting nugget he picked up from a "birdie of a birdie."
The specific thing I heard is that next year's camera might be the biggest camera jump ever. I don't even know what sense this makes, but I've heard that it's some kind of weird two-lens system where the back camera uses two lenses and it somehow takes it up into DSLR quality imagery.
While iPhone rumors are a dime a dozen, especially this early on, Gruber network of "birdies" are on-point more often than not. If Gruber's off-hand remark comes to fruition, a dual camera implementation would certainly help improve overall image quality and photos in low light conditions. DSLR image quality would be incredible, but let's not get ahead of ourselves.
If Apple goes down this route, they wouldn't be the first company to release a smartphone with dual cameras; the HTC M8, released earlier this year, incorporates such a feature. On a related note, Engadget this past February profiled a startup called Corephotonics which developed a dual camera implementation of its own.