The Update Manager no longer shows package updates, but updates (i.e. one line per source package). This means you will no longer see 20 lines or so per libreoffice update but just a few. To give you an example, on my box this reduced the number of updates from 550 to just under 200.
Our policy is for users to be selective when they update software, so showing less information and more relevant information makes a lot of sense.
A Cinnamon update for instance doesn’t need to list cinnamon, cinnamon-dbg, cinnamon-common… assuming you were able to only update one of these 3 packages, it wouldn’t work anyway. So that cinnamon update is now listed simply as “cinnamon” and it includes updates for all 3 packages.
Short descriptions also now appear in the list of updates.
Size and old version columns are still available in the View menu but hidden by default.
Last but not least, the Update Manager no longer hides itself after applying updates.