The main character Duke Nukem is one of the most humorous main characters ever. His quips throughout the game made me laugh more than once. The multiple settings of the game are varied and are equally amusing. It is easy to play the same levels over and over looking for every secret area and to achieve the best speed run possible. This greatly adds to it replayability.
The enemies are varied and challenging. You can always raise the difficulty if you think it is too easy, but the upper difficulties can be frustrating, as it should be. You can end up playing this game for hours at a time and for only a few bucks it is worth the buy.
The best thing about this game is that it is still supported by multiple modding communities, which allows for a unique and varied experience. If you enjoy playing any FPS from back in the day I would definately pick this one up.