One of the most cogent (and, to my mind, accurate) critiques of Barack Obama's presidency appeared this past August in the New York Times. Its author is Drew Westen, a political consultant and professor of psychology at Emory University. It is, you'll notice, a critique from the left, an expression of the sort of dissatisfaction and disappointment that many liberals feel about Obama's presidency.
Here is an article by Julian Zelizer, a professor of history and public affairs at Princeton, who argues that Obama might well be a one-term president and then goes on to offer a look at some previous presidents who have failed to win re-election.