As I read your comment about how you felt Adorno and Horkeimer's essay was "dated," I felt compelled to fill in a bit of background info on these two authors (if you're a Media Studies major, you probably already know this, but if you're not, you'd have no reason to know this.) You're right though, about how they seem to be incredibly cynical about mass-prodeuced cultural forms and the enjoyment of them, like going to a movie simply for the sake of being entertained.
Adorno and Horkeimer escaped Nazi Germany and wrote critical social theory from the Frankfurt School's neo-Marxist perspective. Having had the first-hand experience of witnessing the (propagandistic) horrific power of Nazi-controlled media (i.e. Triumph des Willens, a.k.a. Triumph of the Will) these two theorists were intensely wary of the influence of the media aimed at the masses. I sure would be too!
Even in spite of the "dated-ness" of Adorno and Horkeimer you point out, I do feel however, that these two writer illuminate a few very key matters about mass media and the Culture Industry that are still in play today and should not be ignored . . .
1) Purchases (of mass-produced commodities) made by the individual aid in constructing identity (I find this to be increasingly true--just watch any music video and scan for brands to see who identifies with what products)
2) The culture industry/mass media create common knowledge (wikipedia, to name one example!)
3) How consolidation of ownership of corporations creates a monolithic set-up (a system in which "clones" of each other in the Culture Industry make money . . . i.e. Top Chef and Food Network's Next Star, The Office UK and The Office USA, etc. etc. etc.)
Something that I did not like however--but that I'm willing to admit I probably do as well--is how Adorno and Horkeimer seemed to place themselves above the masses. It was as if they believed they were able to see how the "culture industry perpetually cheats its consumers of what it perpetually promises," while the rest of the masses were too stupid and subservient to notice the apparent brainwashing. (139) Hmmm, do we all assume to be smarter than the "average" viewer or media consumer??