The target of his pamphlet was that large, undecided portion of the population, those thinking that reconciliation with England was possible. His ideas came at a critical time and were widely read. 500,000 were sold in the course of the revolution, amongst a population of 2 million. John Adams said, "Without the pen of the author of 'Common Sense,' the sword of Washington would have been raised in vain.”
The battle he engaged is being fought again. The form then was republicanism versus monarchism. Today it is capitalism versus welfare statism. Both are forms of individualism versus statism. Are we as individuals right in making our own decisions and pursuing our own happiness, or does the government own us and have the right to dictate how we should live?
My favorite quotation is below. Consider that we have two political parties. Democrats are completely devoted to statism and have even dropped their support for freedom of speech (e.g. in 'hate speech' legislation, the 'fairness' doctrine in broadcasting and campaign contribution regulations). Republicans are a mixed bag, with some genuine advocates of freedom and others that would reconcile some economic freedoms with welfare statism (e.g. George W. Bush's compassionate conservatism).
[A]ll those who espouse the doctrine of reconciliation, may be included within the following descriptions. Interested men, who are not to be trusted; weak mean, who CANNOT see; prejudiced men, who WILL NOT see; and a certain set of moderate men, who think better of the European world than it deserves; and this last class, by an ill-judged deliberation, will be the cause of more calamities to this continent, than all the other three.Conservatives, don't think better of welfare statism than it deserves.
(Craig Nelson's biography of Thomas Paine is my current favorite: Thomas Paine: Enlightenment, Revolution, and the Birth of Modern Nations. Recently deceased Christopher Hitchens has also written a biography, which I'd love to read.)