Found a nice article on the importance of collaborative code reviews:
Studies show peer code review is the most effective method for finding defects. One analysis of more than 12,000 software projects said code reviews hit 60% efficiency for defect detection while unit tests were only 25% efficient. For every hour of inspection using peer code review, development teams can save about 20 hours of QA testing.* Not bad.
One of the greatest benefits of tool assisted code reviews is the documentation of the process itself—allowing everyone to learn from each comment and correction made. The other significant advantage is the ability to have code reviewed by developers who don’t happen to be sitting next to you. If you have a development team spread across the globe or a crazy colleague who only works from 1-5am, a code review tool will track any reviews done for authors to view at their convenience.
Code review tools: