When using the side panel for thumbnails, clicking anywhere on the thumbnail is like a soft select, have to click the little box or else if you scroll the document your selection disappears. if select anywhere else on the thumbnail its also very difficult to see what is selected.

Then when you drag the selection to extract, the unhighlights the page use dragged it from so when you want to delete the selected pages after you extracted them, that page is left hanging around.

You should be able to select the thumbnail like in the old adobe, by clicking anywhere on the thumbnail. And after dragging you should be able to just delete the entire selection.

Lastly, in order to rearrange pages you also have to select the little thumbnail box instead of being able to just grab and move the selected thumbnail. Very difficult or time consuming for rearranging pages.