For starters, the opinion seems to pretty well block any future use of the Commerce Clause as a tool for future mandates. In fact, I'm beginning to think we'll soon see challenges to other past court decisions based on the new limitations.
Overturning the Medicaid mandate on the States seems to me to be an implicit decision to return the 10th Amendment [The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people] to its proper place in the Constitution as a limitation on federal intrusion into the State's proper role in government.
The decision to deny that the mandate as constitutional under the Commerce Clause and uphold it under the taxing power of the Federal government seems, on reflection, a wise move accomplishing two goals: (1) it puts into question the status of other fees, assessments, penalties, and 'sin' taxes as methods to coerce 'proper' behavior and (2) it throws ObamaCare squarely back to the Congress for a redo (with the admonition that the Supreme Court reviews laws for constitutionality, not stupidity).
Charles Lane, the Washington Post's only sensible columnist (well, after Charles Krauthammer, of course) put it well on Fox News Sunday's panel when he said (paraphrased) that Chief Justice Roberts is playing chess when his opponents are playing checkers.
For concurring opinions, go here, here, and here. For a dissenting opinion, here's the always readable Mark Steyn.