As promised in my last post, here is my list of a few underrated science fiction novels of the last 30-40 years. The list is not meant to be exhaustive. Moreover, it is definitely not meant to be a list of the best sci fi of the era, merely the most underrated.
1. Norman Spinrad, Iron Dream. This is a great satire of some common shortcomings of the sci fi and fantasy genres. It purports to be a sci fi novel written by Adolf Hitler, who in this alternate universe left Germany in the 1920s and became a science fiction writer in the US. The fake "novel" makes the point that many standard genre tropes have a lot in common with the main themes of Nazi/fascist ideology. I think that Spinrad takes the theme a bit too far, but it's an interesting and fun book nonetheless. Ironically, the book was for a long time banned in West Germany because censors feared that it would actually stimulate support for Nazism (the very opposite of Spinrad's intent, but a possible validation of his point about the genre and some of its more misguided fans). Iron Dream is well-known to aficionados, but hasn't received as much broader recognition as it arguably deserves.
2. Marion Zimmer Bradley's Darkover series. This series has been overshadowed by the author's own better (and more popular) Mists of Avalon. Moreover, some of the books in the series are far from brilliant. Nonetheless, the series has numerous interesting elements, characters, and plotlines.
3. S.M. Stirling's Draka trilogy. I include this one with some trepidation, because it has many weak points, including the unrealistic nature of the "alternate history" elements of the plot, and extremely silly technology in the last book. Nonetheless, the author's idea of a society that is essentially the negation of American ideals is interestingly developed and thoughtprovoking. Stirling manages to make the evil and depraved Draka characters weirdly fascinating, a rare achievement for sci fi villains. The series is also unusual in that the villains, not the "good guys," are actually the central characters. Like Spinrad above, the author has been misinterpreted as sympathizing with the dystopian society he portrays. I should warn also that the sequel to the trilogy, Drakon, is lame. It combines most of the defects of the original series with none of the virtues.