Admin, I'm making the transition and I know I'm in the minority, but there are a few small issues for me. As Jane said, I occasionally have some scrolling issues, but no big deal. By the way, I use Mozilla Firefox instead of Internet Explorer and so (assuming I'm not the only one) you might want to keep this in mind as I am aware that some websites are optimized for IE and not for Firefox. As far as ease of use I like how the topics and threads are in Bold type and moved to the top of the forum if there are new posts or threads. A small suggestion would be somehow highlighting with bold type or something within the thread and creating an automatic "jump" to the first post within a thread which is new to the individual reader, rather than having to hunt through and reread several posts (or check the time stamps) to find the new ones, and/or remember what page and what post was the last you read. This is one area in which the old format was easier for me and you didn't really have to think about anything to navigate it.
Aside from that, my only displeasure would be that with all of the different threads and forums, it seems a little fragmented to me. So keeping the number of forums rather limited and having primarily one "catchall" forum would be something I would prefer personally even though I realize that most probably feel otherwise. The fact that I could unthinkingly proceed on the old forum in a linear fashion and make sure I saw all of the new posts was a strength to me. I'm sure this is probably just my problem as an old non-techie fuddy duddy, but any optimizations that you could make gradually over time to make it mindlessly simpler to use and navigate would increase my enjoyment of the new forum. Sorry for writing a book, but there it is.