If you keep your feathers well oiled the water of criticism will run off as from a duck's back.
Rule of criticism: only attend to the shape, and the purpose will manifest itself.
Science fiction that's just about people wandering around in space ships shooting each other with ray guns is very dull. I like it when it enables you to do fairly radical reinterpretations of human experience, just to show all the different interpretations that can be put on apparently fairly simple and commonplace events. That I find fun.