Now that I have seen the game, it is a contender on my to buy -list.
What it is like by the first couple of hours? It is more like Half-Life 2, there is surprisingly lot of puzzles. Plenty of chuckling comes from appropriately named objects and places. Disappointingly, not all things can be shot to get through, and those iron fences and doors are one that I indeed think the RPG should devastate or go through. Note that it wasn't me who played it, I only sat and watched. But I think it is very likely that PC is the most fluent experience, especially the pig cops tend to cause trouble when they get close and there is no mouse-like precision in controls.
My first impression is that Duke has been modernized, and not all of the changes are for better - two weapon limit comes to mind, as was stated by my friend who uses PS3. It is as if something would still have been lost in conversion, BUT, and this is a big but, I need to try this on PC, the aiming seemed cumbersome on a console. Alien bastards have nasty shields that prevent their ships from being shot down, which was a bit of a disappointment too. Even though environment is destructible, it isn't as destructible as I wished for.
In the end, it might suffer from being modernized while still retaining some of the old, a compromise few might like. As I said earlier, it feels more like Half Life 2 instead of Painkiller. Can't yet tell, but it still seems to be worthy of buying. I need to check the current prices, though.