I took an algorithms course at Harvard. It was just as hard as anything I took at MIT, and I took 18.313 back when G.C. Rota was still alive (greatest math teacher ever, by the way).
Of course there are people who are there because they're "legacies", and I suppose they take different courses, but the kids who get in because they're smart are pretty damned smart.
As for left-wing indoctrination, Harvard is a bastion of the establishment. The prep school crowd in particular has been thoroughly indoctrinated in the perfection of capitalism and the moral entitlement of the ruling classes. It doesn't mean that some of them aren't apostates, of course.