Rather than starting a new discussion, I thought I'd jump in on this one to echo the feedback from others in this thread. While overall I like the new forums, I find them very difficult to navigate for the exact reasons mentioned above. Its difficult to find the unread posts in a thread I'm interested as the sort options dont allow me to read them chronologically from where I left off last time.
I also find it quite difficult to see which threads have new posts in them since there is no obvious visual indicator of that. I liked the big yellow NEW sign on the old forums that immediately showed me that a thread I had viewed had new posts. It didn't require me to "work" to find those tiny little numbers in the bottom of the topic in a pale font that say how many new posts.
Finally, the design where everything is almost the same color and font weight, makes it difficult to distinguish the thread titles from the description texts (that are far to long in my opinion), and therefore make it hard to scan a page to get a quick overview of threads. To me it just looks like a giant wall of text.
Hope this feedback helps these forums improve over time.