It has polls, it supports push notifications so phone apps can immediately tell you about notifications, you can write remarks about users that will be shown to you only next to the user's name, and what I actually find the biggest usability improvement is that I can turn on notifications for any post or any community so that if anyone writes anything to that community, I get a notification. That's awesome with groups that get like one post every two weeks but where those few posts are all very interesting!

Some people also like that you can group a bunch of communities into one feed that you can view as if they were together just one community. Meaning, if there are copies of the same community on five instances, you can opt to merge their content when viewed from your user account.