So one thing that drives me nuts is that when I click "Reply to Thread", I get the Quick Reply box. For the most part this is good for me. Yet when I finish typing, I'm inexplicably drawn to clicking the big blue "Reply to Thread" button again and I lose my post! It would be nice if that button changed to "Post Quick Reply", or if the "Post Quick Reply" button was bigger. (In truth, I think the issue is that the Post Quick Reply button is in the bottom right, off screen, while the Reply to Thread button is visible.
Of course, it's entirely possible that I'm a dough-head too.