Large APS-C (22.2 x 14.8 mm) sensor Large sensor in Canon 450D 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.
524g Carrying this weight all day may not be very comfortable for you.
Body Thickness 62mm With a thickness of 62mm,Canon 450D is not a pocketable camera for sure.