In some ways, this format should be better, with the candidates controlling the debate and confronting each other on their own terms. Usually, the rules put in place keep the candidates from actually debating each other. The debates usually turn into a quiz show with each candidate answering the moderator and people evaluating who gave the best answer.Lehrer got steam-rollered, IMO, and was not a moderator, but a hapless participant. Nobody acquitted themselves well, as far as I could see.
Lots of blather, and very little debating. I had to force myself to watch the full debate this morning. I couldn't get past 30 minutes of that crap last night.
In practice, it made for a messier debate than I'd expected and possibly made it harder for the average viewer to really follow the substance of the debate. I don't know how likely it is to see this format again given the difficulty for a moderator to control that type of debate.
To be honest, it's up to the candidates to control this type of debate, but it's a format they're not that familiar with either. I'd expect it to work better next time (if there ever is a next time), just because the candidates would have an actual example of the possible pitfalls and opportunities.
As far as how it actually worked, I think it diminished the substance and made overall impressions more important - and Romney definitely looked better than Obama.
Did it really give people something to hang on to for the rest of the campaign? Probably not, since that opportunity was also diminished by the messy flow.
But it still goes as a plus for Romney. Just hard to say how much.