Here is a good essay by Michael New reflecting on the 20th anniversary of Planned Parenthood v. Casey. http://www.lifenews.com/2012/06/25/casey-decision-at-20-pro-lifers-make-progress-on-abortion/
As New points out, the decision was a mixed blessing. The Court failed to take the anticipated step of overruling Roe v. Wade. But the Court did open the door to further incremental restrictions on abortion and this opening has led to pro-life gains.