Welp, let's get this over with.
Got the demo, for what it was it was alright. Nothing amazing, but not bad. Pretty much what I expected, with some oddities.
-Regenerating health is, indeed, regenerating health. "Ego" system be damned.
-Infinite ammo supply crates.
-Duke is unusually weak. He begins to pant immediately after sprinting and in one instance needs to take out three empty barrels out of a minecart before being able to move it.
The demo has two levels. First one was pretty enjoyable and very Duke-like. Throwing feces, drawing on a whiteboard, kicking an alien's eyeball for a touchdown, etc. I actually enjoyed this level a lot, despite it being super short.
The second level is a mess. It's focused around variety, which it provides, but the execution is meh. There's that minecart example I gave earlier, but there's also things like a lack of lines or music. Duke makes a wisecrack once throughout the whole campaign ("I SURE COULD USE A CROWBAR RIGHT ABOUT NOW" while in front of a tunnel blocked with the Half-Life 2 traditional "three wood planks" defense) and the "thrilling escape" is nothing more than a silent minecart ride to the exit. No music, no silly Duke. Just you and a minute of a typical minecart track.
tl;dr it's very hit and miss.