RSS feeds. Praise be to Invision, despite all the other issues folks are having. And I'll add some wood to the fire:
I'd love to be able to disable the "attachments" section by default. I so rarely use this feature, and it takes up a bunch of screen real estate (especially annoying on this POS laptop I'm stuck using until I get my home desktop working again).
Also, as to comestibles' questions:
You can still edit posts. The button is next to "Reply" and "Multiquote" in the bottom right.
The friends feature has been there forever, it was just buried in the profile stuff before. You can disable it.
I don't see the "personal conversations" feature, but I don't really see a problem with having more real-time conversations off-forum, if that's what the feature is.
Edit: I take it back. RSS feeds are all chronological rather than reverse-chron. Hopefully that gets fixed soon.