Obama's pragmatism has provoked a good deal of criticism. Much of it rehearses old philosophical prejudices or conflates "pragmatism" in the philosophical sense with "pragmatism" in the everyday political sense - the sense that equates it with opportunistic and unprincipled political realism.
If you want some background within which to situate Obama's approach, you might like to take a look at my new book: The New Pragmatism (Acumen (UK) & McGill-Queen's University Press (US)). It tries to explain in clear and accessible terms how pragmatism offers just the kind of social hope that Obama constantly invokes. And, for a quick take on what pragmatism can offer in politics without encouraging a wishy-washy approach, one that lacks deep convictions, see pp.116-118.