Don't even take this summary with a grain of salt because it is true, sadly. This is basically all you need to know about the candidates.
Mitt Romney: Generally agreed upon as being the front-runner. He's pretty. He has an attractive wife. He has five sons who look exactly like him. His healthcare plan in Massachusetts was the blueprint for Obamacare, he's a serial flip-flopper so much so that jokes have been made on stage, he hates Muslims, and he wants to go to war with Iran.
Newt Gingrich: Lying, cheating, thieving bastard of a man who is currently on his third wife (he left his second wife after she was diagnosed with cancer). He has an intimidating persona, and uses this to convince the public that a correct person is wrong, and that he is the correct one. He almost never is the correct one. He loves sweeping generalizations and scare-tactics. Hates Muslims. Wants to build an American base on the moon by the end of his second-term as President (he has said this officially).
Rick Santorum: Religious zealot. Wants to go to war with Iran, Syria, and everybody else who maintains a laughably weak military. Hates Muslims and gay people.
Ron Paul: The most thorough understanding of economics of basically any person in modern times, thorough understanding of and Originalist interpretation of the Constitution, his Constitutionalist political philosophy has been unwavering for 30 years and he has never been bribed or swayed for political gain, he has refused to accept his Congressional retirement pension because he believes elected officials shouldn't be entitled so such benefits, he has a very thorough plan on how to cut $1 trillion dollars from the budget within the first year of his Presidency, and would finance these cuts in part by cutting all foreign aid to enemies and allies alike and also bringing home our troops from around the world and shutting down military bases that we don't actually need, which is most of them. He believes in capitalism, free markets, Austrian-theory economics, free trade and travel with countries around the world, and diplomacy. He believes in a strong military but thinks war should only be used as a last resort, and wars should be declared officially and won decisively. He does not hate Muslims; he believes in religious freedom as is protected by the Constitution. He does not hate gays; he thinks everybody should be able to wed anyone they want, except that marriage should not be a government institution as it is now, but a function of local churches and organizations where the idea of marriage originated in the first place.