I played the Duke Nukem Forever Demo, and following are my impressions:
1) Yes, the graphics is pretty dated, but not a deal-breaker. If you were expecting next-gen graphic then you're mistaken. The game is delayed by 13 years, for crying out loud... on that scale, the graphic are pretty adequate for the game. Also, call it a weird co-incidence or deja vu, but the original Duke Nukem was also quite behind in graphics department compared to other titles of it's time (iD software games). But graphics were never high point for Duke.
2) The first level is exactly what you've seen in gameplay demo videos so far. You start the level by standing in bathroom, taking a piss. From there you just run around in the building, meet few soldiers in the room, scribble crap on whiteboard. From there you run around some more, find a devastator in another room and go up on the football field where a giant one-eyed monster is shooting rockets at you, sending shockwave balls of electricity at you and even propelling itself towards you. You use the devastator to keep shooting at it while dodging it's attacks. You get plenty of ammo airdrops to refill and in the end you kill the monster by climbing on it and pulling of some pipes. The fights ends with you field-kicking it's eye across the field. The level end with famous cut-scene of two twins in schoolgirl outfit and you (as a duke) playing this whole thing as a game. You know the rest of the details.
3) I have just played two levels so far. It seems there are only two levels, but since I haven't completed the second level yet (I kept dying :ashamed

. But so far it seems the usual Duke/FPS fare. The second level gives you more choices of weapons, but yeah, you can carry only two at a time. You get Railgun, Shotgun, Shrink-ray gun and Reaper. Shrink-ray gun is awesomely fun (shrink your enemies and step on them to crush them and watch the gore spreading on the floor). The railgun is very much like Quake3 (minus the spiral shockwaves). The Reaper is machine gun with multiple barrels in parallel. The shotgun is, well shotgun. This level starts with you in the DukeBuggy driving across the terrain, avoiding air-attacks, rolling giant rocks and killing the alien pigs with your buggy. After the big jump across the valley, you stop because your fuel ran out. From there you advance to alien out-post killing everyone in your path. You can also use their grounded machine guns against the incoming hordes of air-dropped pigs.
So far that's all I've played, but my initial impressions are quite good. Yes, the game has it's flaws but it's still a lot of fun. I'm going to go ahead and pre-order my copy now. Haters be damned. :bleh: