TL;DR - try out the Mailman 3 beta on some smaller mailing lists?
Mailman 3 has a new archiver called HyperKitty, a replacement for Pipermail, so viewing the web archives of a mailing list is a way better experience - you can actually see threaded discussions all on one page. (I won't have to link to gossamer-threads anymore to give people a link to a whole discussion!) Here are some examples:
https://lists.stg.fedoraproject.org/archives/ - a directory of mailing lists
https://firstname.lastname@example.org/ - the listinfo-type page about a particular mailing list
https://email@example.com/thread/CY2YL6HB5QGP73UHXIBRH7BW4RGJJ4IG/ - viewing a thread within a list
https://firstname.lastname@example.org/thread/VDQZW5BTALEJVWNUMVHDTWCC3ZCS6QGZ/?sort=date - possible to view a thread flat-style, by date, instead of nested by replies-to
Right now I'm a little unhappy that I see no obvious way to see the whole archive of threads for a month, the way there was with Mailman 2 - as you see in https://email@example.com/2013/12/ it's paginated and I don't see a "see everything from this month" button or link. Maybe this is configurable by the administrator or maybe if you log in you can set it in your preferences; I haven't checked that.
I also like that people would be able to reply to messages via the web interface, and log in via OpenID.
More about what's exciting in http://terriko.dreamwidth.org/151005.html which says:
"Do remember that the suite is in beta, so there's still some bugs to fix and probably a few features to add, but we do know that people are running Mailman 3 live on some lists, so it's reasonably safe to use if you want to try it out on some smaller lists. In theory, it can co-exist with Mailman 2..."
So I'm wondering whether we could try this out on one of our smaller lists, like design or qa or wikitech-ambassadors?