Bottom line is that All the Old Knives is a really fine and absorbing movie. I recommend it, no hesitation. The rest of what I have to say about it just fills in details.
Spy thrillers on the screen seem to fall into two categories. The first and by far the most numerous is the James Bond path: fill the screen with action and when in doubt, add in more car chases, hand-to-hand fights, and explosions. These efforts can be extremely well done and give you a great thrill ride and if that's what you want, there's no lack of choices out there. But the generic problem with those was nicely nailed by that very wise writer Ursula Le Guin: if the only thing going on is unceasing physical action, that's a sure sign no story is being told. (Or words to that effect -- I had trouble finding the exact quote.)
So then we have the second category: the John LeCarre camp. Much rarer and ultimately more interesting. Sylistically the daddy of all of these is The Spy Who Came In From the Cold (1965, starring Richard Burton and Claire Bloom). All the Old Knives is spookily close to a modern version of that. Chris Pine and Thandiwe Newton play now-retired intelligence officers tasked with getting to the bottom of an 8-year-old unsolved mystery: what went wrong with the way their agency dealt with the infamous Flight 127 in Vienna, taken over and destroyed by terrorists? Was there a mole among them, and who? The story gets laid out for us in flashbacks and replays of their memories (and sometimes flashbacks within the flashbacks), bit by bit.
Here's a spoiler for free: there's not a SINGLE car chase, fight, or explosion. Not one. (There is one gunshot.) This is grittier, realer, and tenser. If you think this is boring -- here, have a lollipop. Go away and let the grownups watch it.
The two stars Pine and Newton virtually carry the whole movie, with a bit of help from veterans Laurence Fishburne and Jonathan Pryce in supporting roles. But they are all excellent and the dialog is impressively realistic, constantly engaging. Following the twists and turns is not meant to be easy, I think, but the scenes connect seamlessly and flow beautifully. Is there a message underneath it all? It's never said out loud, but I think it is just that in this spy business, everybody taking part -- sooner or later, right side or wrong side -- loses. Be prepared to have a mix of feelings by the end.