An easy approach to a more natural way of leaving feedback for another student artist is through a TAG review. This method has been around forever (and is especially common in Language Arts) but it has proven to be quick, productive and benefical for both the reivewer and reviewee.
Here is the method we use.
T- Tell something you like
A- Ask a question
G- Give a suggestion
We start the process by writing the word "TAG" down the left side of a Post-It and leaving our 1/2 completed artworks out at our tables. Music is played and students walk around the room until the music stops, sitting down at the closest artwork other than their own. Students then complete the three letter prompts by commenting on the artwork that is in front of them. When we're finished, all the students have a short peer critique that not only gives them a positive compliment but also encourages them to think about their artistic choices as the project continues.