Until now, I've more or less ignored the changes that came with the "upgrade", but upon further consideration, I have no option but to observe that the change to the notification bell SUCKS - hard enough to drag a bowling ball through a mile of half-inch steel pipe. It used to be it was easily possible to decide which posts that were being announced by the bell had or hadn't been read. Now, it's all but impossible, once I've hit the bell to show me the list, to decide which ones I've looked at and which ones I haven't. Previously, the "untouched" ones were left alone, so that reading one, then returning to the list, showed the one that was just read in a different shading that made the status obvious, and the ones not read still in the "other" shading, easily picked out of the list for action.
Now, hitting the bell shows EVERYTHING that it's notifying me about, and selecting one of them to look at changes *ALL* of them so that it's impossible to tell which ones have or haven't been looked at.
Rollback on at least THAT behavior would be a very good thing. Either that, or some way to say "open all of the new ones in new tabs and dispose of the rest."