Might as well ask "what's the real effect of cars," or "what's the real effect of fedex."
The only real way to answer a question like that is: positive for some, neutral for some, negative for others. I don't think anyone would argue with the proposition that some people have unhealthy relationships with some porn, and some people have had very beneficial experiences with some porn. Porn has split some couples up, and brought others together.
With regards to the "raising expections" argument: what's wrong with that? Is the counter argument that, if we had no physical ideals, everyone would be happier being less than the physical ideal? If so, we need to get rid of a lot more than porn. Like fashion models, TV actors and actresses, sports stars, etc. Me, I don't have any problem with unobtainable ideals like models, presidents, race car drivers, etc. Especially since I'm hardly the ideal physical specimen; maybe they're on to something here.
But, hey, if the mediocre majority want to ban excellence, I'm all for it. It'd be funny. Anyone read Kurt Vonnegut's
Harrison Bergeron?
And I'm not even going to get into the government regulation angle of the original article. Ok, I lied, I am. Our government is in charge of nearly 300 million people. Tens of thousands of homicides and rapes happen every year. The question isn't whether government should somehow "do something" to prevent underage access to porn; the question is whether parents should expect government to drop those priorities in favor of stepping in to legislate and enforce restrictions that could be achieved a lot more easily if parents would just take some responsibiltiy over and control of their childrens' internet access.
Cheers
-b