All we know about such technic as code review. We do it frequently and become more and more happy from one code review to the next.
But I never met such a technic as "feature review".
The idea is to ask developers from time to time to tell about the feature he/she implemented. As detail as possible. And check this implementation for architecture and design cleaness.
I'll try it on the nearest project, I hope. And then report the results.