I'm not very pleased after playing the Deus Ex: Invisible War demo.
The interface looks too much like a console interface would look. It's got big fonts that really obscure your view, whereas DX1 has nice, small fonts that doesn't clutter up a thing. The fact that conversation texts appear as they speak doesn't help either.
DX1 has a nice, sleek interface where you can click tabs at the top of your screen to switch between different views (such as Inventory, Skills, Goals/Notes, et cetera). This is replaced in the DX:IW demo with a distinct key for each window, and no way to switch between them without first clicking Back and then hitting the key for the specific window you wanted.
They decided to merge the lockpick and multitool into, well, the multitool. That was highly annoying. In addition to this, the multitool now looks like a magic wand, emitting orange light onto metal door locks to pick it.
Breaking crates and other objects looks very, very unnatural; just a speck of dust and some small chunks of debris. But I believe they'll fix this in the final game.
What I loved about Deus Ex 1 was the freedom you had. Not only because of the pseudo non-linear story line, but the fact that you could carry your weapons everywhere you went, even into bars. This time around though, the bar in the demo (the Greasel Pit bar) has a "weapon lock" system; they won't let you in unless they use a sort of projection beam to disable your weapons. It had been much more plausible had they ordered you to deposit all your weaponry in their storage room or something.
They didn't do it all wrong. The news bulletins are now read by announcers, which is kind of fun.