Often code reviews are done by one person, the technical lead of your team.

In my opinion it’s better to make each developer of your team do code reviews.

My arguments

1. Having all developers do code reviews leads to discussions about what coding standards should be used..
2. Leading to well-documented standards.
3. Each developer is forced to understand the workflow of an application which isn’t his, which expands his domain knowledge.
4. Each developer learns from others and is given an opportunity to teach and discuss why someone chose a certain path.. There is always something new to learn, even for seasoned developers. You might just pick up that latest trick doing whizbang Silverlight 3 stuff from that freshman that just started working this year.
5. Multiple perspectives on a problem can only benefit the solution.