Come on, everyone should've known that Romney would be like this
Romney has been down in the polls for a month, thus its obvious that he was putting his hopes on this debate. He knows this was his last chance to turn the election. He's an egomaniac that has put a lot on the line with this presidential election (heck, this is what he has wanted for at least a decade!)
This should've been so obvious to everyone, including the Obama strategists. What this did was make him predictable, and thus easy to make a strategy around.
Romney blabbered lie after lie that may sound predictable to people at first, but as some has said, has given Obama the rope he needs to finish hanging Romney (which was probably why Obama let Romney blabber on). We are still 5 weeks away, are people going to remember this debate on election day? No, but Romney's lies and the attack ads that will take advantage of them will last more than this debate in the memory of people.
As others have said, other challenging candidates before that won the first debate lost the election.