libel laws are tricky. to my understanding, you can't be liable merely for stating an opinion (an opinion being a belief or viewpoint which may be supported by reason or evidence, but which cannot be proven true or false through evidence). however, merely framing a statement as an opinion doesn't automatically protect it--if the statement includes or implies the existence of defamatory facts it could be actionable. thus, merely stating that "in my opinion, this dac sounds bad" is protected, but stating that "in my opinion this dac sounds bad because it contains radioactive materials and was assembled by child slave laborers" probably isn't.
looking at this cameron's review, i'd argue that it's classic protected, subjective opinion--even to the extent his opinions are based on (allegedly) false factual assumptions, there's no reason to believe that he knew the assumptions were false, or that said assumptions were defamatory in the sense of maligning dcs. to the larger point, i fully agree that dcs's hissy fit was a remarkably ill-advised, self-inflicted wound--consumers remember this stuff.