Aside from reporting bugs, I think users should not be allowed to make 'I don't like this!' threads for at least a week after the redesign, maybe two weeks.
You may start off not liking something, then come to find that you actually prefer it. These things take time, though! It's only Thursday after all.
I personally feel like this site is taking a step in the right direction. Yes, there are some nostalgic things I'll miss, but soon this design will become nostalgic. There are lots of new features that I can't wait to use, and Tom and everyone have even more additions they plan on including over time. I think Newgrounds needed to be refreshed. It will also likely draw in more users/visitors, and that is definitely a plus (though I hope it doesn't become a new 'Youtube!').