All the one-liners are there, and the game can be challenging at times because the shooting gameplay hasn't changed from DK3D. There's not much cover, and there's no iron sights... you just have to run at your enemies and gun them down Quake style. But for some reason they modernized the inventory system so he can only hold two primary guns at once so on harder difficulties you end up running out of ammo.
Secondary weapon selection is counterintuitive. You don't whip them out, you fire them immediately. For example, you switch guns by hitting '1'. If you hit '2' you immediately drop a trip mine onto the ground infront of you and I've killed myself many, many times this way. Also they switched to the CoD/MOH recharging health bar so you'll often have to run away and wait for your health to recharge (really un-duke like).
Come to think of it, he does a lot of stuff that's un-duke like. At one point you find random tourist sitting on Duke's throne (which you need to sit on, it's a secret elevator). Duke tells the guy to beat it, but the guy won't leave. The Duke I know would've hit the guy in the face. Instead, he helps the guy out by taking a picture of him.
You increase your health bar by doing random things like microwaving popcorn, or playing basketball. They inject backstory cinematics in game by forcing you to sit behind an invisible wall and listen to some guy talk. They tried to throw in some comedy bits by referencing game pop-culture but everything just comes off as in bad taste, especially that pregnator section.
The graphics are terrible, and I'm prepared to keep ripping into the game but I think I've said enough. Overall the game feels like an unprofessional HL1 fan mod except I paid $60 for it. The biggest slap in the face is I can't get the game to run stably on my computer (causes crashes that require a hard reboot), but this might be a personal problem. It prompted me to get DK3D from a friend, and I had a much better time playing the original than DNF.