For illustrations of potential end-user downsides of SOPA and ProtectIP/PIPA, and to do something about them (yes, you), see..
For what a bunch of folks involved in engineering the Internet think, see..
An Open Letter From Internet Engineers to the U.S. Congress
December 15, 2011 | By Parker Higgins and Peter Eckersley
For some further commentary, see the below (this is just some highlights, you don’t have to look far to find a bunch more out there)..