Rated 2 out of 5 stars

yazan: fkhatri tarih: Tem. 20, 2011 ·

It does not group very well, for me.
I have threads with the same subject with 2 people going back and forth, and they do not get grouped.

This review is for a previous version of the add-on (2.0.7). 

yazan: Jonathan Protzenko (Geliştirici) tarih: Tem. 21, 2011 ·

I suggest you read https://github.com/protz/GMail-Conversation-View/wiki/What-is-threading