Large APS-C (23.5 x 15.6 mm) sensor Large sensor in Sony A55 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.
500g Carrying this weight all day may not be very comfortable for you.
Body Thickness 85mm With a thickness of 85mm,Sony A55 is not a pocketable camera for sure.