The author's note at the beginning of this, John Le Carré says that he wanted to do something more real about the spy experience, after Spy Who Came In From the Cold, his first book (and still very bleak, so that's telling!), and that this was the result and people hated it. I can see if you're expecting sexy spycraft, and Smiley outsmarting the best of them (and there is a delight in that!), you'd absolutely be disappointed, because this is a book that is all about the futility of it all. It's men who had their glory days in WWII, desperately trying to regain some semblance of that greatness, and the lengths they'll go to and people they will sacrifice to make it happen. So know that going in, and it's a very sad tale, but a real and honest one. Also Le Carré talks about one of the "loves" in the book is John Avery's love of his estranged wife, and like sir, politely, sir, he repeatedly talks of his love for Fred Leiser, and there is very much a queer undercurrent that is interesting to note.