For the 14 days that I had the iPhone 6 I too found it challenging to consistently take clear pics. Where the iPhone seemed to excel is macro shots. Outside of that the photos were just okay.
I actually preferred my S5 and Note 4 camera.
By "clear pics" do you mean pictures that don't look like they are taken through a dirty window or a layer of smoke?
I am puzzled by what could possibly cause that. Usually that type of problem indicates moisture in the camera lens. Other than that, I can't think of another intermittent cause.