This game is one that marked my teen years. I must confess that I never finished all levels. That is because all time was spent on multiplayer. It was pure joy. Everything from level design which punishes camping to the weapons that are designed to humiliate your opponent (like shrink ray :)). Duke always had insult for your opponent (Alt+Fx) and you couldn't get bored with it.
Although I bought it, I am afraid to start playing it now. I know that I am grown up man, with wife and children, but I also know if I play only one game with my friends, it will be impossible to stop.
You can find little bit longer review with some hints at: http://medo64.blogspot.com/2009/03/uka.html