The protocol should be able to find same files in other torrents - you could be downloading a bunch of files (like a season of TV), but are able to find and download one file from another torrent that is better seeded (like one single episode torrent). But I don't think any of the clients implement that yet.
There are lots of changes that are nice-to-have efficiency improvements.
But there are no new killer features. I would guess that the extra user headaches from having outdated software not work with new torrents will exceed the benefits of slightly faster downloads and slightly better availability.