After reading a couple of only average Silverberg novels, it's great to have my faith in the author's ability reaffirmed by reading another of his greats.
Like [b:The Book of Skulls|1408114|The Book of Skulls (SF Masterworks, #23)|Robert Silverberg|http://d.gr-assets.com/books/1183368204s/1408114.jpg|1876966] this is almost only incidentally SF, that is more character driven than anything else. Yes, it is about someone who is a telepath, one of the classic tropes of the genre, but it is never really rationalised or understood. But that wasn't really the point, rather it was about how someone coped with being different from everyone else with an ability that was as much a curse as it was a gift, and how he coped with the fact that he was now losing his ability.
The Protagonist David Selig isn't a particularly sympathetic character, one gets the feeling that his problems are largely of his own making rather than a result of his unique gift. He spends much of the time wallowing in self-pity and bitterness, he is clearly his own worst enemy. And yet the character feels real. This is a frank appraisal of his own life and relationships with others. One cannot help feeling moved by his experiences while at the same time one wants to shake and shout at him to sort it out.
A great book and one I would recommend to both genre and non-genre fans alike. Sometimes I think that the best SF is written by people who are unconscious of the genre they are writing in and this is another case in point.