Dense, Elliptical
Conrad's writing can be very difficult to follow, since he has a tendency to start a sentence going in one direction, to change direction, then change back to his initial direction before the sentence is even over. As a reader, you might find yourself reading the same sentence two or three times (if you've got the patience to do so).
You can see an example of this meandering prose in the following sentence:
At last Michaelis rose, and taking the great lady's extended hand, shook it, retained it for a moment in his great cushioned palm with unembarrassed friendliness, and turned upon the semi-private nook of the drawing-room with his back, vast and square, and as if distended under the short tweed jacket. (6.4)
The sentence starts by talking about Michaelis getting up and shaking the woman's hand, then talks about him turning away, then takes another moment to throw in a few adjectives about his back, and closes with a phrase beginning with "as if." But by the time you reach the end of this sentence, you're no longer even sure what this "as if" clause refers to. It's simply your best guess is that it's referring to Michaelis' body. Dang, Conrad. Now we need more coffee.
Throw in a couple more hundred pages of lines like this, and you're going to get pretty tired. Conrad seems to write this way because his thoughts are always moving between different objects without drawing entirely clear connections. This leaves you confused, but you're in good company… many of his characters fail to make connections between the isolated details of their lives.