My very quick take on the debate:
No game changers and no clear winner. O'Malley was more polished, Ehrlich had a chance to answer O'Malley's ads.
I think that O'Malley crossed a line with his reference, twice, to the use of "coded language" during the discussion of student performance in Baltimore. It was a thinly veiled accusation of racism and I think that it was so out of left field that it tainted O'Malley's performance. Ehrlich says that the "being born poor should not determine the quality of a child's education" and O'Malley responds by accusing Ehrlich of racism. It was not O'Malley's finest moment.
Ehrlich's insistence on giving the final closing statement was just a bad moment for him. Who cares who goes first, O'Malley was happy to go first or second. The exchange diminished Ehrlich in comparison and his closing statement wasn't especially powerful or focused so I'm not sure why he cared about the order.