Code review, done properly, should provide more than just a critique of coding style. It should should also catch certain types of bugs before they get to functional testing. Yes, you can catch those same bugs in functional tests, but in the environments where I've worked, there's a lot more overhead (read: time, money) involved with bugs found in functional test than in code review. Ita can be pretty frustrating to be that far along (functional test) and find a bug that could've easily been found in code review.