Is it just me, or is the Silver Age aesthetic en vogue right now? From Alex Ross' Justice to Darwin Cooke's New Frontier (more on both of those later), it seems like the area from 1960-1975-ish is being mined pretty frequently. This is undercut, however, by how much all of those projects rule. As is the case with Red Son, it seems like everyone's respect for the Silver Age makes them work to their best.
Red Son is in many ways, only theoretically about Superman. My reading (which not everyone would agree with) is that it uses the Superman mythos specifically and DC at large to tell a story about moral relativism and the impact super-humans can have on politics and philosophy. The moral issues in particular are key to the story; in many scenes, I found myself cheering on the absurdly intelligent Doctor Luthor, defender of America, and more than once Superman commits what I would call unforgivable acts.
As with many "Elseworlds" titles, Red Son features alternate versions of mainstream DC characters. Some are the "same" as their counterparts having led alternate lives, such as Lois Luthor (nee Lane) and Jimmy Olsen (who eventually finds himself director of the CIA). On the other hand, many are odd parallels to people from the regular continuity, like Piotr Roslov, a twisted doppelganger of Pete Ross.
If you don't know who Pete is, then many of the subtle references may escape you. However, even if you don't know who the Atomic Skull is, you'll get the bid stuff and will be able to enjoy the story all the same. The point of the story is not hidden among these Easter Eggs, but if you get it, you often can't help but smile.
On top of all that goodness, the writing is solid and the art has a simple, 60's sci-fi/superhero style that's perfect for the flow of the story and action. It feels like a cop-out to put that all in one line, but I dare you to read this story and think about anything other than the quadruple twist ending, which actually fits perfectly while still leaving you breathless from awesomeness.