Okay, I played some 2 hours Duke Nukem Forever, and I like it.
It's certainly not on par with HL2 or Crysis 2, but it's still solid fun. It reminds me of the old days of Half Life 1 or Quake 2 where shooters were still level design driven and puzzle driven, so, no cutscene bull****, no objectives a'la "secure that bridges till the choppers come", no artificial drama, nothing that could deprive the experience for just being pure and straight forward.
Graphics is also better than I thought. Is it just me or does the Unreal Engine 2.5 actually look better than 3? Well, probably a matter of taste.
If you are a Duke fan, buy this game.
If you're shooter fan that wants a break from all the boring Call or Duties and Halos or Battlefields, buy this game.
Otherwise, wait for a price drop.