using object reposotory has more advantage. It has few 
disadvantages also , it's based on scenario on which we are 
going to automate.In our application , we are having same 
kind of objects in different pages, during that time we can 
use descriptive protgramming instead of having the same 
object repetively in all the pages it ll consume more 
space.bbut it's preferable to use OR in qtp.