An OK sequel
What I liked most about Human Revolution is how the developers exercised a good deal of moderation in dumbing it down. For example, they introduced regenerating health, which is normally considered a dumb feature, but they also made the weapon damage high and the regeneration slow, thus negating some of the dumbness. They removed skills, but deepened augmentations. And so on... Overall it's nowhere near the disaster Oblivion or BioShock were.
In some ways, it's better than the first Deus Ex. The dialogues are deeper, and there seem to be more choices and consequences (I only finished it once), the graphics are of course a lot more detailed, and the engine renders the atmospheric environments well. I liked it a lot better than the shiny Unreal3 look from other contemporary games. Performance is fine too (at least on DX9.)
Aesthetically, it's quite pleasing. The Detroit area is the weakest. The other hub has some beautiful environments, and the missions have their striking moments too (except a certain dock mission, which is both visually boring and poorly motivated).
The side quests are interesting. Most of them somehow tie into the augmentation debate - the brainwashed mercenary-assassin who starts killing his employers, the prostitutes who are forced into augmentations to enhance their clients' pleasure (yikes), etc. They are comparable or better than anything the original had to offer.
What bothered me the most was that they changed the gray, realistic visuals from Deus Ex into something that reminds me more of cyberpunk anime, which makes it lose some of its impact. For example when a character talks about private security forces as 'capitalism's final encroachment into one of the most lucrative industries' it's actually quite a deep thought that's relevant to our modern world, but because it's said by a cartoonish character in a cartoonish world, it will hardly register.
Then there are the three unavoidable boss fights that happen in small rooms and can only be defeated by shooting them long enough (and it does take a long time). I don't know why they put these in. Deus Ex is about being sneaky and clever. It's not about shooting a tank-like character in the face fifty times while dodging infinite bullets and grenades. It's almost like fighting bosses in a platformer.
Then there's the small stuff, like the third person cover and take-down mechanics, the much more game-y interface, the use of a quest compass (which is useful, but only because the map is so useless), lack of detailed locational damage, skills, lockpicks, etc.
The main storyline events are really dumb. For example, at one point, you have to figure out a freighter's destination. Well, we're the head of security of a mega-corporation in a cyberpunk setting, so how will we approach this? Will we attach a tracking chip to the ship? Will we watch it from orbit? From a plane? No? A boat then? How about hacking a computer for the schedule, or interrogating a dock worker with our arm blades? Nope, hobo Jensen decides he's going to hide in a cargo container to see where it's going.
The Bottom Line
It's... okay. It's better than Deus Ex in some ways and worse then Deus Ex in some ways. In most ways it's the same - and that's the problem. It's been ten years since DX1 came out, and one expects a certain amount of progress and increase in depth which Human Revolution hasn't delivered. It could've been more open, the world could've been more reactive, it could've partly simulated an economy and ecology, whatever. It could've been different, but instead it is too much of the same.