Apple support forums quote few users apparently having issues with iPhone 6 Plus OIS or AF actuator. The image appears blurry and wobbly and phone is audibly vibrating. It's not known how widespread is this defect, but many web sites talk about that: Phonearena, Daily Mail, BGR, and more. Only iOS 8.1 devices reported to be affected so far. A Youtube video shows the defect:
Other video demos are here, here, and here.