Large APS-C (23.6 x 15.6 mm) sensor
Large sensor in Fujifilm X-Pro1 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.
Medium size Body
With relatively smaller body compared to DSLRs and better ergonomics compared to Compacts,Fujifilm X-Pro1is a good compromise between size and functionality.
Carrying this weight all day may not be very comfortable for you. Body Thickness 43mm
With a thickness of 43mm,Fujifilm X-Pro1 is not a pocketable camera for sure.