Let's get something straight right from the get-go: TUBE isn't SHIRI ... nor does it try to be. While Woon-Hak Baek is the genius behind both of these films, he's created two entirely different vehicles ... both with their own unique narratives ... and one shouldn't enter into the TUBE expecting the political firestorm that was SHIRI.
However, what one can expect is a great action movie that tries to hard to be something more than a great action movie.
The premise is simple: T (Sang-Min Park) takes control of a crowded subway train, loading it with explosives so that the authorities risk detonation if they try to stop it. However, Detective Jay -- vengefully hunting the terrorist who killed his fiance -- manages to board the train, and he spends the bulk of the film trying to outsmart (and, when necessary, outfight) someone he's always been one step behind.
So, yes, the film can clearly be compared to SPEED as well as DIE HARD, to a lesser extent, but what those films lacked in depth of character Woon-hak Baek goes to great lengths to create here. However, when the film slows down to focus on character, it slows down too much. Too many secondary characters are given a backstory (or a B plotline) that weighs down the narrative with some unnecessary emotional baggage (in SHIRI, Baek focused on principally three characters, hence the greater success). Inevitable choices still have to be made, so the emotional depth ends up being thrown in for the sake of ... well ... being thrown in, and the end result is a bit of a mess.
Character elements aside, however, TUBE moves along briskly as a convincing action vehicle with some solid special effects.
While the disc is slim on extras (there is a music video and a "making of" featurette that's far more promotional than it is informative), TUBE is still worth entering for the sheer thrill of the ride.