It's slower to start writing a post. It no longer has player stat integration, which was cool and should instead have been mirrored to be like ingame so you can check K+A : D and not just K : D. What did the new forum give us? I don't know. Step back.
I've been looking into why the new editor is loading slowly for some users. In the mean time, you can just disable the full editor and use the basic one if you prefer:
Scroll down to "Message Editor Interface" options
S2 Games: Dedicated employees serving dedicated gamers. Continuous development. Never-ending improvement.
Yup and the interface is just a small improvement (in terms of what you have access to). But what's missing is that you cannot check player stats through forums and the overall image isn't as good as before.
It is slower for sure.
Looks prettier though.