Both. IIRC, the only alternative FPS to play was Doom 2 or Quake, which had very little character and focused on the action.

The Duke Nukem engine was (from my point of view) on par with Doom's engine, but their level design made playing the game a lot of fun. From seeing yourself in the mirror, to kicking toilets and fire hydrants, the world seemed much more alive than any other game at the time.

The game had a fun boy-ish "I'm gonna kick ass" vibe to it that isn't really seen today. Most FPS action games nowadays, while fun and entertaining, seem to take themselves too seriously. Musclebound Marcus Fenix is too brooding, and Roach too focused on terrorist plots to really portray the giddiness that was found in kicking a pig in the face with your manly boot.