In my group I have Erin, Ella, Phoebe (and me of course!) , and I think we work really well together because A) We all like the book and, B) Well, there isn't really B at all!
I think our group really chose the right book because it was the one we all wanted, and whenever someone is reading, everyone is always respectful and listens to the speaker (reader :)
If I could change one thing in the group it would be to have a few more people in it. I do like having a small group but it would be nice if we had a big group, so there would be more people to share your thoughts and ideas with.