Constructive peer code review is really high up there for code quality and improvement. (Perhaps the #1 driver)
Both participants learns a lot from the discussion, and the feedback is really useful, if done in a constructive manner.
You also find a lot of issues in your code, when you are required to explain it to another person. (Ie: Wow, I am embarrassed that I wrote that, I guess I should clean it up before the code review...)
I would recommend finding a way to do frequent and small reviews, as opposed to huge code reviews.
As far as the mechanism, I am unsure. As the only developer, who do you go to do a review? (Proprietary code is an issue)