Actually DCM has a good performance characteristic and it is more easier to design controler  for DCM converter , But in DCM operation all component has a high stress specially mosfet , diode and inductor current . in practice it's not recommended to use DCM operation in power rating more than 150W. 

Yes , what Kazemi told is correct, DCM is ok for low power converters. Due to stress on components reliability is bad.

Also the discontinuous operations at higher power cause havoc with EMI. CCM is to be preferred at higher powers.