Capitivating? Well, not really. Not a single character is such that you are able to care what happens to them.
Mere survival? Of course everything is eventually mere survival. Somehow the question seems to not make sense with regards to this novel. And that is good.
If it had been me, could I ever have bothered writing this? I don't know. And that's just gushing praise coming from me.
Plot, characters or setting? Characters. And a damm good job of that.
Will I remember this book at all? I seem to think about the secret agent here and there as I ponder whether a very few bizarre people in real life perhaps are secret agents. Why is this guy a secret agent anyway? For being such a good job of characters it's really not clear at all. But then people in real life, ultimately have such unexamined motivations quite often. Where if they ever bothered to look at themselves they might just disintegrate and blow away into nothingness.
Then there is the ending. The typical inability to comprehend one another. It could stick with me.
Lots of points for being an incredibly negative story. Conrad's most negative I've heard. He actually apologized for it being so damm negative.
But it would be nice if some of these characters were such that people referred to them with regards to the real world. They aren't quite such that that can really happen. Some things are touched upon too subtly. Other things aren't quite talked about really. Perhaps they would get in the way of primarily telling a story.
I guess it has that worry of being preachy. So instead to an extent that which could be of long term use just slips by unnoticed.