It's an intelligent creature feature, that offered great scares, laughter and some genuinely tearful moments. It also bitch slaps the political landscape (and doesn't cast the US government in a good light). It packs a lot into its story but doesn't come off unwieldy or unfocused.
There's always a great sense of space and place in a Joon-ho picture, of precise movement not only on the primary action, but in the peripherals - he's a master of misdirection, world building, and creating fully fleshed out losers, who toil and fight on and maybe, just maybe manage to get it right at the end (but at a cost). In addition, within this whirlwind of bureaucratic idiocies and creature attacks and kidnappings, there's a portrait of family, illustrated so memorably in a sequence where a ghost, a memory is fed and cared for during a meal.
This was a film I liked on a first viewing, but with each watch, it grew and grew in my estimation, I now consider it one of the best of the genre, and some of the director's finest work overall. (a personal Best Picture nominee to boot).