Here we have the story of a future dystopian society with shades of Brave New World-esque classism/racism at perhaps his penultimate peak and an effort to overthrow it and return to a darker time as seen through the eyes of our protagonists.
Beyond this Horizon is one of Heinlein's earlier, non-juvenile, works. While many of his later themes are present, its clear he's still working out some of his political and philosophical ideas.
As is the case with any Heinlein, there is certainly misogyny, an unfortunate seeming fondness for both libertarianism and fascism (somehow), and in this case some definite hints of racism/elitism/classism. 
However, due to being an early work, I think this and several other works give us what may be hints that Heinlein perhaps did not agree as wholeheartedly with some of those distasteful ideas we believe due to his mouthpiece characters espousing them. Maybe even that, in some way, he's 'devil advocate'-ing these ideas and philosophy.
A good example of this is the oft-(partially)quoted by the NRA passage about a polite society being an armed society. Besides the issues with it only being a fragment of a quote, and lacking context, there are certainly contradictions presented here. From everything he wrote, we see Heinlein viewing being armed, and even personal violence, as perhaps fitting with interpretation of the quote presented by gun advocates. However, the individual making that statement in this very book insists he prefers to go unarmed, and that sort of personal violence should be considered crass and distasteful, that we would better off if no one was armed. 
There are similar contradictions in his famously negative view of socialism and pro-capitalist/libertarian stance. While as usual characters may denigrate socialism vocally here, we also see that this post-scarcity utopian society only continues to function as a 'capitalist' one because annually wealth is redistributed among the population based on complex computations, and that the government is continually looking for projects that benefit and enrich society as a whole to throw money at, since 'production' is largely unnecessary. These are very socialist ideas, and presented in a very positive light...but are somehow still framed as being capitalist?
If for no other reason than looking at these contradictions that either indicate Heinlein is still working out his ideas, or had been playing devil's advocate all those years in some kind of grand jest, this is definitely worth reading.