When talking about Duke Nukem 3D even people who enjoy it struggle to put into words why they like it so much. People who don't know will say it was having an action hero pastiche, others will say it was the "interactivity" as in being able to play biliards in one level. Duke 3D actual biggest strength it's his level design, levels that are still to this day looking actual places while allowing gamey stuff to happen with small narratives and setpieces in them, no memorable story obv but levels leading into one another at the exit rather than just dropping you there and amusing theming in the levels adds a lot to it. Duke 3D actual loop is also pretty good and standout for the genre, with the core loadout from the first episode being usual but slightly different to further additions like the Shrinker and Devastator being nice and fuctional gimmicks, sadly there's also the Freezethrower and a good chunk of actually useless weapons and items, not many games are designed around the fact that the player could have a jetpack on themselves at all times though.

Episode 1: The most iconic the game gets and probably a good reason why the saying that the freeware episode in a retroshooter is the best one is said to begin with. This is as tight as the game gets not the other episodes aren't to look forward too.
Episode 2: Drop down in quality but not as severe as a lot of people make it out ot be. Levels are still really good but plagued with the overuse of suicide drones and less varied in their colors.
Episode 3: Back to earth with more colorful and better levels.
Episode 4: Pretty nutty. There are a lot of annoying encounters but over this is Duke 3D at it's limits.

Duke Nukem 3D is still to this day a standout in the genre with it's design and unique gimmicks. And it's still probably the weakest in the Build Engine Trinity.

As someone who was looking forward to this hoping for it to improve on what I disliked about the original I'm overwhelmend by how much better this sequel turned out to be.

I disliked the original because it was more a 2D dark souls and I'm not really fond of that formula anymore. This game follows the metroidvania beats far closer with it actually having movement upgrades that while basic all make traversing the enviroment more enjoyable and come with lots of challenges. The the new weapons you can get are all great even with the clear superiority of one over the others and interestingly early on dictate the routes and upgrades you can get since these weapons have specific interactions with the enviroment allowing you teach otherwise unreacheable places. Generally the game's got a great rythim with exploration and rewards and only gets less interesting when you run out of new places to see and things to do by the end. Impressively even the visuals are better, shame the cutscenes are no longer obscenely detailed pixeld art

People might take issues with far lower difficulty but that's mainly due to your chatacter being much much stronger. The real issue are enemy types who lunge forward at you, have fun taking damage as you wake up because their on top of you.

If you had a decent impression of the original or just want a great game in the genre be sure to play this.