In most cases, they have become good friends. This has been very helpful for students who are not outgoing and might have remained isolated. My guess is that this helps such students not to withdraw from the course or the college. In some cases, students have made great progress in learning how to negotiate with others, how to explain mathematical or other concepts to others, and in listening skills. None I could report.
Students become aware of others' mathematical difficulties.
Some adjust to the needs of other students. They seem to gain some skill in organizing themselves and in communicating clearly with each other. The class itself is also more open. Students are more involved in their own growth. But then, it hadn't been too bad before.