Isn't this a bit like Chinese Democracy by Guns 'n' Roses? Meaning that all that time and money invested have raised the expectations to levels than can never be satisfied?
On a more serious note, the Chinese Democracy effect would apply if it were still under development by 3D Realms. Gearbox has turned out a lot of great titles so I have faith in them that they'll make this a good game. I don't know what to expect from it, but they do know that Duke was all about fun(especially since he was a parody to begin with). I'm not expecting the game to redefine first person shooters but I think it'll finally shake off the notion of it being vaporware. Hopefully no other well-deserving franchise gets this kind of treatment again.