I suggest you increase the visibility of this change, perhaps by a link/article on the main GR page.
It can be quite disconcerting for a newbie to see that the forum 1) looks completely different (having lost its GR "look") and 2) you can't log in anymore.
Primarily to make it clear you need to perform the "request new password" procedure (whic I just completed myself).
And prominently displaying what to do if you're unsure on how to do this (perhaps as simple as "send an email to the webmaster"). I'd specifically call out the "I've lost that old email adress I used to register ages back " case - how do you change the "registered email adress" when you can't log in?
(I suspect there is not automatic procedure and that the answer is "email me" but I believe this should be spelled out specifically and separately)
Also, your call for forum skin suggestions deserves to be lifted to prominence (based on the fact that this thread has no replies, and a quick skim didn't reveal any other discussion)
Finally, how about adding a link to this thread in the Announcements forum. At least that's where I looked for information first. And it would keep this thread handy even after falling of first page here in General.
Just a few quick thoughts
PS. Let me clarify that I am having no problems myself - this post is offered merely as suggestions to improve the forum makeover in general.