I'm not a Romney fan either. I did not vote for him in the primaries. I held my nose on election day because I genuinely thought he'd at least be better than 4 more years of Obama. Maybe there wouldn't have been much difference.
I think their would have been significant differences. Romney would have done stupid stuff. We wouldn't have had Obamacare, but Romney might have tried to pass some sort of Obamacare light. The Repubs probably would have passed some form of Amnesty which would suck.
On the positive side, Benghazi probably would not have gone that way if it happened at all. I doubt Romney would have been so quick to kick out the leaders of Libya and Egypt like Obama. Not sure of Romney's stance on Afghanistan after getting Osama. We seem to be languishing there now accomplishing very little. Overall, Romney would have done dumb stuff, but I don't think he would be actively trying to destroy the country.
Looking at specifics, there are probably a lot more differences good and bad. Hard to say what the Democrat media would be harping about or trying to push Romney on if he had won.