I don't know that anything in
Brüno was
really that exceptionally offensive or otherwise out the usual fodder in that genre. If anything, I thought the idea was lazy, compared to
Borat and otherwise (though obviously, there were some commonalities also). The movie really didn't bring anything new after
Borat, and just lacked a point. Even with its funny bits. Which weren't too many.
Honestly, though, imo the R-15 rating
Brüno got in Finland was hugely inappropriate, when R-15 here means that 13-14-year-olds can also go see the movie when accompanied by an adult. I took my younger sister, soon-to-be 14 at the time, to see the movie. Sure, I'd seen the trailer, she'd seen the trailer, so we didn't exactly expect a PC-treatment in any respect, but R-15 does not say full frontal nudity to me. It neither says penis close-ups nor penis-copters. R-18 (which is the next one up here) says penis. R-18 tells me I'm going to see a movie that isn't suitable for younger audiences, and that I shouldn't take my 13-year-old kid sister to see it -- after all, I couldn't.
Both of us laughed at the scenes out of sheer surprise at the time, but had I known of the full extent of what the movie contained, I would
never have taken my sister to see it.