Rated 4 out of 5 stars

It seems I can't actually post a new review, only edit the previous one so I hope this actually gets read.

Yes, Developer, you are correct that in Gmail the messages themselves don't change position and this is as it should be but the latest date received is sent to the top. Does this make more sense?

This review is for a previous version of the add-on (0.6). 

You're not missing anything - that's by design. When a new message arrives this extension will bubble the entire thread to the top of your inbox, but the thread itself will remain in the order the messages were received (with the newest at the bottom). I've never seen a threaded view operate differently (gmail does the same thing). Thanks for the feedback though. :)