I listened with interest to the two speeches at the NAACP Convention. While I thought the coverage of Romney's was a bit off (explained below), both speakers accomplished their objective.
Let's start with Biden. Biden is prone to malaprops and this one was remarkably free of them. He only mispronounced one word. He gave a good partisan speech (albeit with some distortions of record) to a liberal group. Biden has a long history with the organization and he clearly was speaking to friends. In the last election, the normal role of Vice President as attack dog, was muted because the GOP candidate and the media did a lot of the attacks themselves. This time it is clear he will be the attack dog in chief. I believe that a lot of the Obama campaign will be negative because besides Osama and Obamacare (which is still pretty unpopular) there is not much to run on. Obama's economic record has been dismal. So the BS that surrogates like the DNC Chair have handed out (with the willing assistance of some members of the media) like the "felony" claim will be the major focus of the campaign. What I especially liked about Biden's speech was its genuine sound. Many politicians, including the President, adopt a colloquial sound (dropping gs is one example) when they speak to an African American audience but Biden did not.