It's too early to say whether CISPA is ready to be "opposed," or even if it will survive. But there is
a dearth of definitive legislation about proper handling of personal information apart from a few American laws like HIPAA, and about exactly how and what information can be shared among companies or between companies and the government. Right now, no one knows for sure.
You can go to the Library of Congress web-site and look up the actual
draft legislation and the various commentaries concerning it, which are prepared for legislator use. I generally suggest that you should do that, instead of reading merely about how much
is being spent "for" or "against" it.
You should never
have "an expectation of privacy" with regard to the Internet ... and you should also be mindful that a sword cuts both ways. Some of CISPA's (proposed) provisions are actually meant to increase
privacy by setting forth regulations concerning "geo-location" features and other things that right now are sending information without your knowledge or consent.