My two cents:
As I see it, Obama is a Democrat and a liberal democrat (or, as Europeans would put it, a "social liberal" or "social democrat"), but certainly not a socialist or even Marxist, that would be a huge exaggeration. But his policies make me think he believes in at least limited public responsibility for social fairness, which you may like or dislike for good reasons (and it's ridiculous to believe his policies are "socialist", or that he even believes in genuine class warfare or revolution of the working class, or abolishing private ownership of the means of production). There are several European politicians and parties who go even further regarding social fairness, who are still not socialist or even Marxist.
And he's black. That gives him naturally another perspective on American society and history, than rah-rah patriots from the right. The latter often completely ignore the bad sides and badmouth everybody who points them out, or just acknowledges them, as "hating America". Blacks, even when they are patriots who believe in America and love it, naturally don't have such a white-washed and rah rah view on their own nation. I do believe Obama does love America and is a patriot, but just because of that, he believes pointing out shortcomings in racial integration in order to improve them is necessary, because that's true love for your country -- you want it to become even better.
But then, I may not entirely understand the details of American political debate, because I am not American. This is just my impression.
Maybe that's why I have a problem with whites accusing blacks of racism in general: Blacks have been discriminated through American history and still are disadvantaged (their income and education average is still considerably lower than that of the majority, asfaik). White racism against blacks still exists, although it may be much more subtle than it used to be. And whites now projecting their own racism on blacks by calling them "racist" is one example.
But maybe I'm wrong. It just strikes me as similarly wrong as Germans blaming the Jews for the Holocaust, for example.