If you are unfamiliar with Sandel's work, I'd strongly recommend dipping in to his collection of short pieces Public Philosophy (2005). Many of these essays were written for The New Republic and are both accessible and thought-provoking. A former intern journalist in Washington on the Houston Chronicle (where he witnessed Nixon's impeachment) he is a superb writer.
Sandel's critique of liberalism, his main contribution to academic political philosophy, is a central theme: he wants politics to have a vision of the good, not just protect rights to freedoms. But along the way there are interesting thoughts on many aspects of civic life. His brief polemic against what he calls the 'civic corruption' of state lotteries, for instance, (they bombard the most vulnerable citizens 'with a message at odds with the ethic of work, sacrifice and moral responsibility that sustains democratic life'), and the false hope that they bring, shows his unwavering commitment to the values that he believes should be at the heart of politics.
I wrote a short summary of his book on the ethics of biological enhancement, The Case Against Perfection: Ethics in the Age of Genetic Engineering, here, and also interviewed him on the topic last year for the podcast Ethics Bites.
There are a number of free videos of Sandel in action available online here. An outstanding public speaker and lecturer, his lectures on Justice at Harvard are attended by over a thousand students each session.
And, amazing, but true, he was the model for Mr Burns in The Simpsons!