Speaking as an American, I can't really tell from this snip exactly which meaning of "great" the speaker/writer intends, let alone whether irony is intended. The middle class -- those who work to produce and also earn enough to consume significantly -- is often said to be responsible for America's economic success. Furthermore, "middle class values" (hard work, personal responsibility, mainstream religious belief) are also supposed to contribute to America's strength as a nation.
It does seem as if the speaker/writer may be intending to slight the middle class, but I can't tell for sure.