Cropped sensors have [longer depth of field][1] at similar aperture and field of view, which might be beneficial in some cases (macro, photo-journalism, low-light, manual focus based on expected distance) or detrimental in others (portraiture).


  [1]: http://photo.stackexchange.com/questions/10079/can-a-smaller-sensors-crop-factor-be-used-to-calculate-the-exact-increase-in-d