Performances all believable, comedy in the right places, and a pacing and runtime that doesn't leave you peeking towards the exit before the credits.
For someone who didn't really know the story, the details of what went down truly interested me. They did a solid job of not telegraphing the plot points.
Some may find the lack of change of scenery tiring, but I think it worked in this case. I think they wanted you to feel like the control room is your world, and to feel as they did on this eventful day.
They touched on the political and emotional elements nicely. Making you think, without preaching.
Mixing in footage from the actual event, including broadcast footage as well, definitely draws you more into the experience. A nice touch.
While it's not a movie I really intend on rewatching over and over, it is a very well done piece that I'd recommend to friends who enjoy movies like this.