Despite being a sequel, you don't really need to see the first film to understand this one. Aside from the opening scenes and the main character returning, this has absolutely nothing to do with the first film. The story here while nothing original, is an entertaining crime thriller that will hold your attention and is nice to have after the first film was so thin on plot.
But story is not what will be getting audiences into the theater. Of course, it's the action and saying it delivers is an understatement. This film has hands down some of the greatest action sequences ever put on film with everything from hand-to-hand combat to quite possibly the greatest car chase sequence of all time. Even with the amazing action sequences in the first, this puts them to absolute shame. The film does not shy away from the brutality either and all the blood and gore an action fan could want is on display here. You will definitely find yourself cringing in the best way possible at more than a few of the fight scenes. Even at 2.5 hours which had me nervous for a film of this type, it never drags and actually feels about 45 minutes shorter than it actually is.
Believer the hype, The Raid 2 is one of the best action films ever made!