As someone totally new to the franchise I can give you a resounding:
It's far too silly for all the brutal violence on display and for the pathos that 47 and his story with Victoria is trying to convey to properly sink in.
There seems to be an overwhelming amount of options yet also a real feeling of railroading to how one should proceed through the levels. Experimentation is rewarded if it was thought of by the level designer and punished if not sticking to one of the, admittedly, many scripts.
These options are almost so abundant that it doesn't really reward organic, on-the-spot thinking but instead creates a reward for trial-and-error. Something that should be in the game, where one can recon a level or area without the risk of penalty so that a real plan can be formulated. Instead, I found myself looking around for what was obviously a series of events the level designer put together to allow the player to move forward, although possibly with a feeling of satisfaction.
A personal bugbear that I have are these challenges that are associated with each level and their unsubtle presentation.
It just bugs me that you, as a player, have to replay the levels to do some of the challenges as completing some will lock out others.
As I said before, the characters have no personality or establishment other than 'these guys are douches so it's ok to kill them'. The banter between NPCs varies wildly between empathetic to just freaking weird. Like no human being would talk like that, even if they were a caricature.
In fact, that's a good way to describe the characters as caricatures. They have very little establishment and are just suddenly thrust upon the player as 'voice in the ear guy' or 'evil ex-boss guy' or 'bent cop guy'.
It looks good though. The much touted Glacier 2 does deliver on the crowds, even if many of them seem to be ghosts one can simply walk through.
A lot of the levels, although stereotypical, do have a certain 'lived in feel' although they fail to carry the same kind of meta-story as many of the areas in a game such as
Fallout 3 or
Deus Ex: Human Revolution.
Overall, it's too silly to be taken seriously and too restrictive to enjoy the silliness.