Conrad's prose is reliably gorgeous, but I didn't find this novel particularly compelling. All the things you might expect -- suspenseful double-crosses and deceptions, or penetrating insights into the mind of the terrorist, or the tensions between his political and domestic life -- are completely absent. In fact, one has the sense of a fog hanging over the book. It's the same kind of thing you get in Heart of Darkness, but there, it's the arises and part of a meta-reflection on knowledge and storytelling. Here it's indirection and vagueness. Events are almost never related outright, but usually rough a prism of secondhand information or newspaper reports. The minds of the characters are amorphous and confused; this initially makes them seem complex, and later does the exact opposite. Specific scenes, such as the descriptions of Stevie, the musings of the Chief of Police, or the anguish of Winnie, are completely incredible, but overall, the story drags and seems clumsy in its construction.
Incidentally, I also re-read Chesterton's The Man Who Was Thursday today, and it remains a totally fantastic metaphysical story about being a double agent. Such a great book.