Deus Ex: Invisible War pales in comparison to it's predecessor.
The story holds itself and keeps you in the Deus Ex universe. It's entertaining and you have the same choices as the original title and keeps a philosophic view point on post-human scenarios. The end keeps you thinking and, even if the game in itself isn't great, you'll want to play through again to know the consequences of alternative choices.
The gameplay is where Invisible War falls to the bottom of the barrel. The skill system has been eliminated. No more weapon, hacking or swimming proficiencies. There's half as less biomods, narrowing even more the customization. The shooting is good, but too easy -- like the game. And it's way too short. It took me less than five hours on Normal difficulty, and that's taking the time to complete all secondary objectives.
In short, compared to Deus Ex, Invisible War is a failure. It's short, way too easy, there's no customization and oh god do we hate the universal ammo. But for the sake of the story, it's still worth it to play, especially that it's a pretty unexpensive game by now.