OK, first of all, this ruling does not mean that corporations can give unlimited money to candidates. What it does mean is that they themselves can run ads on any subject, including supporting or opposing a candidate. They can not coordinate with a campaign either, so theoretically they could do more harm than good. Under McCain-Feingold, perfectly legitimate organizations like the NRA or NARAL couldn't run adds 60 days before the election for or against a candidate, in other words you have the right of free speech, except when it actually matters. Also McCain-Feingold did nothing to decrease the influence of special interests, if anything it increased it, since the harder it is to collect money, the more influence the lobbyists have, and their influence has only been increasing in spite and because all of the laws.