Another possible formula
Code:
=IF($R2="",IF(SUM($P2)=0,"OUTSTANDING",IF($P2<$I2,"PARTIAL","COMPLETE")),IF($R2="CANCELLED","CANCELLED","PARTIAL ISSUE-CANCELLED"))
The main difference from Marcia's one - it allows canceling entries, where nothing is recieved yet. And the formula assumes, whenever anything is entered into REMARKS column, it means the entry is canceled (maybe different name for this column is a good idea)!