There's lots of debate coverage - but I'll throw in my bit too.
The phrase that struck me was "I know how to do that" - with absolutely nothing to back it up. Not on taxes, not on immigration, not on foreign policy, not on jobs, not on anything.
Especially on balancing the budget. "I know how to do that - I did it in business, in the Olympics and in my state". Except that, no, he didn't:
In business - his business model took business after business bankrupt - the very definition of not being able to balance the budget
In the Olypmics - he needed tons of federal (tax) money to bail them out
In MA - he raised taxes to balance the budget, which he has refused to do as POTUS
So, no Governor Romney, you DON'T know how to do that.