Fantastic atmosphere and action sequences backed up by strong, complex characters and an engaging overall plot. I don't know if I'd say the story is unique really, as it uses a lot of spy movie cliches and tropes, though to me it felt more like a well-made ode to a good spy movie/book/show than a tired retread of the genre. It's silly at times (the English dub really adds to this with its American voice actors doing a variety of accents that can be described as British-ish), but the production values are good, and I was surprised by how much I enjoyed every episode--even themore episodic ones that in another show might feel like filler. Good stuff!