Founded by the engineers who started Yahoo Groups, it has a cleaner look, and I find it easier to use.
If you do try it out, here are a few tips in setup, after you pick your group name (which will be your group email, at groups.io. Be sure to make your group messages private!).
[li]Go to Settings and select Restricted Membership[/li][li]Uncheck “New Users Moderated”[/li][li]Give Subscribers the ability to Upload Files (under Files, near the bottom of the page)[/li][li]Add your own picture for the Home Page! (top bar, under Settings)[/li][/ol]