If you want to view information just like the old forum do this:
1. Choose the "discussed" tab. This will show you the threads with the newest comments (that's how the old forum threads were ordered)
2. Jump between the forums by clicking on their name in the top header. This is the same list as the old forum but is now on every page so you don't need a forum index page.
3. If you want to see the threads in the classic forum style click on "text only" in View Options.
That's exactly the same threads and sorting as the old forum. The advantage is you can jump between forums easily without going to the main forum index. If you want to see a stream of all the most recently submitted and commented threads then chose "All" instead of a specific forum.