I saw Tinker, Tailor, Soldier, Spy about a week ago and thoroughly enjoyed it. I was in a packed theater and everyone seemed mesmerized. There was no whispering, no coughing, barely, or so it seemed at times, any breathing. I think people are perhaps just starved for old-fashioned (in the best sense) movies that are well-acted, intelligently scripted, suspenseful, and (at least to an extent) emotionally involving.
That the Cold War is long over turns out not to make much difference in how one takes in -- or I guess I should say, in how I take in -- Cold War espionage tales. They are, in essence, morality plays, however layered over by ambiguities, and morality plays are a very old genre. Their appeal doesn't depend on the contemporaneity of the factual setting.
The absence in Tinker of the sorts of 'action' scenes (car chases, explosions, etc.) that a Bond or a Bourne movie contains is an advantage in several ways; for one thing, the tension is heightened gradually, incrementally, rather than being interrupted periodically by gigantic pieces of metal being blown up (or whatever). The focus is on humans and what they are saying and doing, rather than on gadgets, things, and special effects. (There is a gun fired in one scene at the beginning and in one at the end, and that's it as far as on-screen discharges of a weapon are concerned.) This movie is, to get very pretentious (but only for a second), an unalienated spy movie, one that has not been estranged from the genre's essence.
Apart from The Russia House, which I don't remember too well, I haven't read much LeCarré. This afternoon (I'm writing this on Sunday evening) I picked up a paperback of Tinker, Tailor. Yes, the movie tie-in edition, but what can you do? It was the only one on the bookstore's shelf.
P.s. For another and somewhat more -- how shall I put it? -- baroque take on the movie, see here. That post has, among other things, the near-mandatory historical allusions (e.g., the Cambridge spies) that I've omitted here.