The Plot
The developers try to present the consequences but they are far too afraid (or lazy) to allow these dramas into the actual plot. Everything seems to happen off-screen, and you only get to see the aftermaths of the events of the game. This is entirely the wrong approach as the player will be in the position where he cannot properly be invested in the passion of the victims in the drama. This could develop into an interesting objective standpoint for an upcoming conflict, but sadly it only builds up to a conflict during the end of the game. The rest of the time, Jensen spends his time mostly running errands for his boss.
This makes the player feel like he isn't important to this plot of augmented humans. No cops are after him because the player is augmented and the rebels are not that eager to interact with Jensen either. The player just doesn't get to be part in the actual drama. If the player could, then this could have been one of the first games to be praised as being computer game art.
The plot fails especially in the third act where the player feels like he doesn't really achieve anything. I'm not going to spoil the ending but many will say (and I agree) that it was very underwhelming.
The Stealth and Combat
The combat however is not that fun. Enemies have a tendency to have a lot of health and the player have a hard time finding enough ammunition to satisfy the massive amount of ammo requires to fall one of the buggers on any other difficulty setting other than Casual.
Here is where the developers clearly misunderstand what made Deus Ex so good. The combat in Deux Ex, some would argue that it's very bad. Personally I thought that it was the absolute best blend between RPG and FPS in regards of how guns work (you shoot a dude and he is dead or dying, easy as that) but in Deus Ex Human Revolution your guns do very little while the enemies guns have a tendency to take you out fairly easily, despite you having superior training and equipment. This is such a colossal misdesign that all RPG developers seem to fall into these days. They seem to believe that in order for an combat encounter to be difficult, that the opponents needs to have massive amounts of health. However, Deus Ex Human Revolution does have headshots, so if you have a good aim you can take anyone down with one single shot. That is bullshit if I've ever seen it, but it makes the horrible combat tolerable.
The RPG Elements
The problem isn't that it's in the RPG system but rather that you need to spend so much to able to hack efficiently. Why is this such an issue you might ask, it is an issue because it doesn't allow players to play Jensen as they want to from the get-go, but the players will have to wait until they've spent 15 praxis points on hacking until they're able to commit to any playing styles. Clearly this is something that the developers could have decreased the importance of, or at the very least give it to the players for free.
Level design
1) Many levels seem to be guarded to the brim and with dozens of locks doors plus even the odd robot guard. Making the game feel like infiltrating a modern castle.
2) The city levels, where you're able to take sidequests and unwind are unnecessarily large and confusing.
The first issue isn't all bad. It is after all the most well designed part of Deus Ex - Human Revolution, but sadly despite being very well designed all of the maps tend to overstay their welcome and the developers doesn't offer enough variety to truly make them stand out. In one part of the game I were confused two times into believing that I somehow had went in circles into the very same office area I left, this never happens in other games! The variety the game does offer is in it's overarching themes over the areas. You see, the areas in DXHR seem to follow themes, so most of these themes stand out really well but the themes themselves seem to be there for far too long.
Conclusion
The game is good, very good - but it's bogged down by all of the minor issues the game has and the relatively minor amount of game time that it offers. Thankfully the issues doesn't ruin the experience and I recommend this game with 4 out of 6.