There was a lot of stuff on that old forum that was lost when it went down. Most Witcher 1 mods were there. Some of them you could only get there. I made my play through of the first game during that time and there was a fan mod that fixed a certain broken part of a quest that I wasn't able to get. There were also fan translations of some of Sapowski's works that haven't been officially released in English yet.
I haven't really checked extensively yet but I do hope they managed to get all that stuff back up. There's a lot that goes in forums. Sure there's bitching, but there's creativity too. Plus the developer's forums for better or worse are always going to be the central hub to a game's community. If you take that away I think you lose something.