Romney is in striking distance in most polls while being hammered on all sides in the primary. That's good news for him.
I think he'll pull out a narrow victory a la Bush 2004.
The primary attacks have barely touched on Romney's big weakness: his years as a 'vulture capitalist'. And that is exactly how team Obama will portray him, if they have any sense at all.
(Although the primaries have certainly opened other wounds, especially among women, that will likely keep hurting him all the way up to the November.) Americans are not well disposed towards Big Business or the 1%, and Romney is basically a poster-child for both groups.