However, it has been known for a long time that the later a defect is found in the software lifecycle, the more costly it is to fix it. Reviews can be used to find defects early, even in the requirements elicitation or design phase. I think reviews should be used in conjunction with tests, since they are complementary. The one is more effective in finding certain types of defects than the other and vice versa.
In my opinion, many software projects could benefit from employing a lightweight review technique like Peer Reviews using state-of-the art review tools like Atlassian Crucible.