In the sense that people now know a lot more about the Lib Dems and some of their policies, then yes. The debates have also got people who usually don't vote to think about politics and maybe turnout will be up by 5% or so this time. So that also has been a success. But there is a down side. The focus of the debates was very narrow and now the novelty has worn off, people will very quickly get bored of them. Also it seems the whole general election campaign has suffered. Coverage has focused far more on how the leaders 'performed' and on their personalities than on party's policies which can only be bad for democracy.
In the long run, I happen to think that unless the format is changed quite considerably to be more like the Question Time format, with a wider range of party leaders involved over the three or more debates, then this new Americanisation of our politics can only be bad. Party's will even more have to think of image and good looks when they chose a leader. Policies will become even less relevant and of course policies really should be the only thing that matters not the least important thing. This can only help the right-wing in the long run. These debates were focussed on three very posh white men 'slugging' it out like a boxing match. It marginalised women and minorities - it was like a first-past-the-post debate. We need to see a wider range of people and politics if we are to engage the widest possible sections of society and make them feel they have a say in our democracy. If the Tories get a majority of seats in this election from just, say 36% of the vote - it will be a travesty of democracy and with the changes the Tories are planning for boundaries, our chance of getting electoral reform might be even further away. Saying that I am more positive about getting a referendum on PR and winning it than I was a month ago.