I think losing the old button that pulled up the newest posts was a major loss. I see no point in the "What's new" button we have now. I've also marked everything as "read" but they keep showing up.
I do love the preview that comes up when your arrow hovers over the subject. I think we're losing a lot of interaction because we can read the first few lines and moving on to the next line. Before, I might have clicked on a subject and read some or all of the replies and commented myself. Now, I could be losing a lot of information by skipping the whole thing after reading the little preview.