On the board view, the notifications sidebar has changed to the _infinite scroll_ pattern.
As far as I can see, reputable practitioners agree that this is a terrible UX pattern which should never be used, except maybe if you're tailing a build in TeamCity.
One of the side effects is that the link at the bottom of the notifications sidebar to the notifications-only view (https://trello.com/username/notifications) is gone. Browsing notifications has always been one of the weakest aspects of Trello, but at least the `/notifications` view lets you systematically work through all you've missed without fiddling around in a small modal sidebar where it's easy to lose your place.
The new homepage looks like a step in the right direction, but it is very information-poor, with most of the space taken up by static lists of boards. It doesn't allow filtering, mixes all kinds of update together (due dates, comments, etc), shows me my own comments, and wastes space in the card display too. And it uses the "show more" variant of the _infinite scroll_ pattern, instead of paginating.
To replace the Trello notification system, I've created a Mentions board using Butler for Trello. This adds a card link to a checklist per board for all mentions and assignments. This allows you to follow up and check off notifications systematically. It would be great if Trello made better use of its notification system.
Sorry for being a squeaky wheel, use Trello every day ;-)
