I have to sound in here and say I do NOT like this new forum layout.
It's not that no one likes change, it's when the changes made makes things more difficult. I can't believe that anyone likes having to go into Settings > Storage on their device... just to eject a USB device, rather than just pulling down the notification shade and ejecting it right there! Yes, I know... it's just an example, but the ease of using something, anything, is what's important to me rather than "material design".
I spend a lot of time here, but just yesterday when the new design launched in my browser (desktop), I seriously thought of dropping out. Yesterday, when I opened the site in my browser, it went to the new design... I closed all tabs, cleared history, cookies, cache and closed my browser... then I even cleared DNS cache... then I opened up AC again and the new site was still displayed. I then went through the same clearing, and then the old layout showed up. Today, (right now), I'm in the old layout. I'm not really sure if the new site is live or not, or what caused the new site to pop up yesterday and revert back to the old layout today.
I'm in agreement with many others that the new layout is not pleasing. Unless there's a way to choose the old style over the new, I'm really considering leaving AC if/when my browser finally decides it wants to always show me the new style and I can't change it back.