It works differently now in that there is no page refresh when you click. You have to refresh the forum (or go back to the index) to see that the forum and threads have been marked read.
Is it a hassle to have the page refresh? It's OK if it doesn't go back to the forum index but it would be nice to have the page refresh so you can tell that something happened when you do mark the forum as read (i.e. the bold new threads turn to non-bold read threads). No big deal really but that is how I read the forums and mark them as read.