I have not read John Le Carre's Tinker Tailor Soldier Spy, though after seeing this adaptation, I'd like to. It seems fairly clear that there's an interesting story being told, but in condensing it down to 2 hours, so much detail has been lost that the result is a confusing muddle.
Gary Oldman stars as George Smiley, a recently ousted British intelligence agent who's brought back for a secret mission. It's the early 70s, the Cold War is in full swing, and there is apparently a Russian mole at the very top of the organization. Smiley is tasked with finding him.
There's a marvelous cast of actors here. Ciaran Hinds, Toby Jones, David Dencik, and Colin Firth are Smiley's four principal suspects; Benedict Cumberbatch is his young assistant; Tom Hardy is an unpredictably rebellious agent; John Hurt is the former director of British intelligence.
But the screenplay by Bridget O'Connor and Peter Straughan condenses the story so tightly that every single line of dialogue is freighted with significance. You barely have time to breathe here (and don't even think about taking a restroom break); if you miss a small detail in the first five minutes, you're likely to spend the rest of the movie confused by everything that happens.
You have to remove some detail when you turn a novel into a movie, but there are limits, and Tinker Tailor Soldier Spy goes well beyond them. You can't shrink a novel, especially a complex espionage tale, down to a haiku and expect anyone to make sense of the results.