Judging from the articles popping up on JU it seems there are some mixed reactions to the new JU format. I suppose that's to be expected whenever any major changes take place. As with anything new there will be a learning curve and a bit of an adjustment period before most people get comfortable with the new format. And of course there will be some bugs to be worked out, which is also to be expected whenever one deploys thousands of lines of code.
So far I have found one or two minor things that annoy me a little, like the fact that the forums system no longer remembers the last comments I read in a thread and I have to scroll through to find where I left off to see any new comments. Hopefully that one will be fixed at some point as it was handy to revisit a thread and have it automatically take me to the last comment I previously read.
All in all though I have to say that the new format is quite nice and I think that once everyone adjusts to it and learns their way around it they will find it far better than the previous incarnation. Change can be upsetting to many people, but I think in the end this is aa change for the better.