If the iPhone camera was as bad as a few people claim, it would be shouted from the rooftops in every review, and every other brand would use it as a huge marketing opportunity to show how much better their phone cameras are.
I think many of us who experience the problems agree it seems to be in the software (except the blur the aperture can create in some images). Maybe it’s just some devices, or there is something in the device configuration, but obviously several users are reporting issues.