Well, on the desktop version there are two buttons - 'reply' and the '+ in bubble' thingie. The +-thingie lets you mark several posts, which you can then reply to at the same time in the 'quick reply' box at the bottom of the page.
On the mobile version there is just the 'quote' alternative, which works well, but then you can only reply to one post at a time. It isn't a major thing at all, but the other function is just so much better IMO.
