In a way, The Left Hand of Darkness isn't a difficult novel to read. Le Guin is a fluid, vivid writer, and her prose never feels trying, boring, or difficult to read. You always know what she's talking about, and it's rare to read a passage and then think, "Wait, what the heck just happened?" It's a page turner, and thankfully, you won't have to be turning those pages backwards just to make sense of the proceedings.
But sometimes you can read a chapter and think, "Wait, what does this have to do with anything, ever?" Take Chapter 2. It's a Gethenian "hearth-tale" that has nothing to do with Genly Ai and doesn't continue the story from Chapter 1 in any foreseeable way. This can make the novel difficult, not because it's hard but because you have to pay attention and connect some of the pieces yourself. By the end of the novel, it's clearer how the chapter extends the novel thematically and how it parallel's Ai and Estraven's story.
Our point is—hang in there. It can be a difficult climb in some places, but the view at the top makes the climb well worth it.