Environmental Sealings For a camera that you carry everywhere with you, being weather proofed is a big advantage. You will have one less thing to worry about.
Large Full frame (36 x 24 mm) sensor Large sensor in Canon 1D X III ensures a good low light image quality compared to smaller sensor, and it also provide shallow depth of field and a nice blurry background when needed.
Large Body Even the smallest lens attached to this body will be a burden to carry everywhere with you.
1440g Carrying this weight all day may not be very comfortable for you.
Body Thickness 83mm With a thickness of 83mm,Canon 1D X III is not a pocketable camera for sure.