If we took down everything somebody wanted us to take down, the Internet would be worse. Right now, under the DMCA, we require the person making the complaint to send us a complete DMCA take down notice. ... We respond by notifying the person who posted the material, giving them a chance to make a case for why the material is non-infringing. ... The SOPA dramatically alters the careful balance in favor of "alleged" copyright holders.
In other words, it will make the Internet worse and put good sites like this out of business.