Sophisticated and Metaphorical
Maybe sophisticated is putting it lightly. At the end of the day, Henry James' writing style is DIFFICULT. And it's not just because the dude writes some of the longest sentences you'll ever read. It's because he writes them over and over again, creating paragraphs that can span several pages.
For example, just check out his description of Paris: "It hung before him this morning, the vast bright Babylon, like some huge iridescent object, a jewel brilliant and hard, in which parts were not to be discriminated nor differences comfortably marked. It twinkled and trembled and melted together, and what seemed all surface one moment seemed all depth the next" (2.2.8).
To read this sentence, you have to understand James' reference to the Biblical city of Babylon. Then you have to follow his metaphor about how the city is like a jewel. Then you have to visualize how looking at the city through a jewel would cause your vision to blur. Now this might be fine for one or two sentences, but try reading it for 500+ pages. James has a way of creating metaphors and building on them line-by-line until you get so lost in the metaphor that you forget what he's talking about to begin with.
You might wish that the guy were more straightforward with his writing. But that would be a Woollett, Massachusetts way of thinking. It's common for us to just want everything to be nice and clear, like being hit over the head with a hammer. But James is trying to show us a different world, the kind of world represented by Paris in Strether's eyes. It's a world of writing that makes you feel like your eyes are following the details of a painted china teacup.
So yes, the language twists and turns and takes you in weird directions. But if you just relax and give yourself to the experience, you might end up having the kind of experience Strether has once he decides to stop fighting the beauty of Paris. Profound, ain't it?