Wait, no. All possible angles have been covered! So let me just say that I agree with most of what Megan McArdle says here -- Bruno is pretty funny but thinner than Borat, and seems not to realize that there's a difference between laughing up (at the powerful) and down (at the powerless -- and add a couple of spoiler-free points.
First, I think Sacha Baron Cohen had a much harder trick to pull off this time around. This is partly because, as the film confesses, the pool of available dupes diminishes with exposure. (They can trick Ron Paul and Paula Abdul, but they can't score Harrison Ford or Mel Gibson.) But it also seems to me that Borat is a much easier character to work with: He's an empty vessel. The average viewer (or at least this viewer), couldn't tell you the first thing about Kazakhstan, much less pinpoint the place with any assurance on a map. And that kind of unknown is the perfect cipher for testing the limits of American tolerance and ignorance.
I imagine this is much harder when the object of everyone's supposed prejudice is the character that Baron Cohen is playing. It's no doubt easier to stumble along with the anti-Semitism and misogyny of a man with a strange accent a funny moustache than to express outright bigotry at the person holding the microphone. The scenes that end up working best aren't the ones where Cohen tries, with agonizing persistence, to tease the homophobia out of some unsuspecting old fool (eg Ron Paul), but rather the ones where he tests the scruples of some spotlight-obsessed aging star (eg Paula Adbul).