One odd thing about the setting though - ignoring the strange way that everyone you meet constantly twitches and writhes like their pants are full of especially itchy nanobots - is how black and white it usually is. In the side-quests especially, we kept waiting for dramatic plot twists, betrayals and difficult choices, but none of them ever really happened.
True, Deus Ex didn't have many of them either, but a bit more twistiness wouldn't have gone amiss in the wake of games like The Witcher and Vampire: Bloodlines.
Very occasionally, something will hint at something deeper, like offering a callback to a previous choice you made or a character commenting on how you handled a particular situation, but that's rare. Beyond letting you choose to simply not to take on some tasks, the main storyline is kept on strict rails until you make this game's inevitable Big Choice(TM) - to the point that Jensen frequently ends up doing mindblowingly stupid and naive things in the (jarringly low-resolution, pre-rendered) cutscenes to keep it on course.
Bam! You just got Jensened!
On a minute by minute basis however, the freeform spirit remains strong. Human Revolution follows Deus Ex's template of giving you big, fully created areas packed with secrets, and making sure you can solve every situation in a number of ways. As in other games based on this template, those ways are typically shooting everyone, sneaking past them, or hacking things using a minigame that starts off fresh and clever, but soon becomes a pathetically easy chore that's far too time consuming for the limited rewards that most terminals offer.
The main changes to the status quo are that your health now recharges, and the shooting/sneaking is now built around a cover system.
The health recharging is a surprisingly small deal, mostly because you still die incredibly quickly regardless of what protective upgrades you're packing. There's still a resource management element for energy, used for both your instant take-down melee attacks and various augmentations, kept limited by the fact that only a fraction of it recharges on its own. Also working against you is that Human Revolution is also spectacularly stingy about ammo, especially if you favour specific guns, with no melee attacks beyond the one-hit takedown. Not being able to at least punch people gets silly, but other than that, the changes are solid.
Find out why Eidos included a cover system in Deus Ex: Human Revolution in this combat feature
The crux of it is simple; that you're never invincible, but nor are you ever left with a single limping health point, or without options. The cover system works too, not just for straight slugfests, but because most of the best fights happen when you're pinned down and trying to think of a clever way out of trouble.
It's no achievement to catch the AI acting wonky, but it's usually a fair opponent; they'll not bat an eyelid if you go behind a box to cloak yourself, but they'll get aggravated if you do it right in front of them. Meanwhile, guards will have their states reset after a while, so it becomes impossible to screw yourself over for a whole map just because of one slip-up. We also really appreciated the way that NPCs guarding an area like a city block will typically order you to leave and *actually give you a chance to do so* before turning the town into a warzone.
Playing stealthily hasn't been forgotten either, and is just as valid as breaking out the heavy rifles. The number of Jensen-sized airvents can get silly even by Deus Ex standards, but are always welcome. Against guards, you get much more feedback than before on where people are and what they're doing, making for a good balance of planning your approach and having to react on the fly. You could call that being dumbed down, but it works, making stealth more about using the information around you.