All of the people I have talked to 1) like Clinton's speech because, their words, he spoke to them as people who could understand complex wonky issues and 2) because, again their words, he actually made a speech nominating Obama to be President which dealt with all of the reasons why he should be re-elected.
A professor friend of mine once told me that the best teacher is the one who can explain the most complex subject matter in the simplest, easy to understand, terms and manner. And I was reminded of that when I listened to Clinton's convention speech. He's an excellent teacher, and he gave a great, and informative, lesson explaining why no President could have turned this economy around in less than four years. He made a much better case for Obama than Obama has been able to put forth for himself, because Bill's simply a better teacher.
I think Clinton's convention speech mattered because it actually had substance, and intelligence, behind it. It exposed the shallowness of most of the Republican rhetoric I heard being leveled at Obama at their convention in Tampa. The Republicans seem to be hoping the electorate isn't bright enough to really understand how deep and how severe this current recession is, and what a reasonable time-frame for recovery might be--regardless of which President had been sitting in the White House since Bush left office. Clinton, in that speech, provided all the Democrats with a lesson plan they can continue to use to to educate and persuade voters, and make their case for Obama's re-election.
Clinton remains very popular with the American people, with high favorability ratings, even before his convention speech.
Ahead of his address to the Democratic National Convention on Wednesday night, former President Clinton has hit a personal best in approval ratings, according to a Gallup/USA Today poll.
The poll, conducted before both parties’ conventions and released on Wednesday, shows Clinton with a favorability rating of 69 percent — higher than President Obama’s, Vice President Joe Biden’s, and even higher than popular first lady Michelle Obama’s numbers.
His wholehearted endorsement of Obama may also help to boost Obama simply by association with Clinton. Currently, they're running Obama ads featuring Clinton, probably for that reason.
So I definitely think that Clinton's convention speech mattered, and will continue to matter, and may help to pull in more independent and still undecided votes for Obama. I also thought that speech showed just how unified the Democratic party is right now, and Clinton's speech was the evidence of that--Obama needed him, he really needed him, and Clinton showed up and delivered. That's in marked contrast to the Republican party, which has factions pulling it in such different directions that Romney wound up being handed a party platform that he doesn't entirely endorse or support, but which he's got to accept, because he really doesn't have all that much clout as the leader of his own party. It's hard to know who Romney will be answerable to, even within his party, because it's hard to know who's controlling, or actually leading, the Republican party these days. If nothing else, Clinton showed that the Democrats are now a united front.