Let me start by saying I love MobileRead, I'm always telling people to visit here. The new forum structure makes it easy to find a forum and easier to search.
However, it makes it impossible to browse. I don't come by every day, and the ~7500 threads in the Sony forum (277 pages) are unmanageable. I used to like to browse the new posts on reader accessories and see if someone had found a cute new case. Now those are just part of an unending stream of threads. The top page is all threads with new comments today. Removing all the sub-forums (sub-fora?) makes it harder to see topical things without paging through screen after screen of new entries.
I like getting both Sony halves back together, but it was at a significant cost.