Sontag represents a certain type of "intellectual" who is - thankfully - becoming increasingly rare in the world of google and broadband...this is the school of people who think that truth can be discovered solely through rumination - without doing any research, without experimentation, without any investigation of the world outside of your skull. It is pure subjectivity - gloriously self-referential and egotistic, completely self-contained and titannically self-satisfied. What Sontag's writings are about are Sontag - not the world as it is (and which can easily be fact checked) but the world as seen through the coke bottle lens of Sontag's ego and self.
In Photography, Sontag is at the Acme of her (witch) craft. She thinks (and enough critics seemed to have agreed with her) that a well written sentence implies veracity as if the good sentence was a litmus test for truth; as if grammar and a good thesaurus conferred reliability, sanity, or common sense. It doesn't.
Pretentious, pseudo-intellectual concepts (on the level of a clever college freshman's thinking), awkward writing (trying too hard to find academic-sounding words), in general, just plain silly. Sadly, our universities are full of people who read stuff like this, write stuff like this, and assign stuff like this.