If the choice of a VP mattered obama should be really concerned with Joe "foot in the mouth" Biden as a running mate, and a fucked up economy.
Generally the man doesn't (or shouldn't) matter. You choose someone inoffensive and obviously ready to step in and assume the duties of the commander-in-chief. Romney, inexplicably, opted not to do that.
So now he has a young career politician whose private sector experience is localized behind the wheel of a Wienermobile and, more importantly, who is the embodiment of the GOP's draconian, slash-and-burn agenda. People
like Medicare. That alone would've been reason to steer clear of Ryan. Choosing a VP with baggage is rarely a good idea, particularly when it's part of an ill-advised "we're losing, quick, shake things up!" strategy.