Lightroom used to remember which filters I use such as the five-star rating, flags etc in the bottom right hand corner. Now everytime I start the app I have to manually select which filters I want in the drop down menu. It isn't the worst thing in the world but it's annoying not having it as accessible as before.
Furthermore, there used to be buttons that would filter out all images that have been edited or not edited in the same area. That is no longer visible. I believe the icons used to look like a few horizontal lines with plus/minus symbols.