If this thread was primarily about what Obama was saying then I think it'd be more fitted to below the line - but it's much more about how he says it, and about the craft of speaking in public, and that's a topic which is in its way inseparable from other aspects of public performance.

I can understand what people mean by saying he's not a great orator, but I think they are missing the point. It's rather like saying of a performer, say Pete Seeger, or Dylan, that they aren't great singers, because they don't have technically great voices, or use the techniques of singers like Pavarotti. It's quite true - but it's irrelevant, because they are doing something different, and they are doing that different something outstandingly well. (A different something in those two examples.)

Obama is uneven, in the sense that it is only on occasion that he has risen to make a really fully effective speech. I think his speech when the Jeremiah Wright business blew up qualifies, and so does the speech at the 2004 convention that pushed him into the limelight. That's not unusual - I don't think too many of Lincoln's speeches measured up to his Gettysburg Address, and much of Churchill's public speaking was relatively run-of-the-mill.

No different from performers really - much of the time it's going through the motions in a workmanlike way, but hitting the heights now and then.

And often enough, in both cases, it's at least as much down to the audience as the performer to enable that to happen. And also down to the occasion and the context.