^ Few other games will make you grumble under your breath in frustration like this game will.
The premise is sound, the execution is spotty at best.
Some missions are ridiculously easy and over incredibly quickly, with only a single objective, whereas others will drag on for a couple dozen minutes as you painstakingly attempt to carry out a perfectly executed sequence of events in the right order, without alerting a single soul. One mistake and you'll very likely have to restart the entire mission all over again.
The latter example is where the fundamental problem with the game's design comes to the foreground - the programming and coding for this game is sloppy. REAL sloppy. Inconsistency in multiple areas of the two most important parts of a stealth game: the A.I, & the physics. E.g:
Enemies will see bodies through walls or platforms above their line of sight, or at other times will ignore corpses right in front of their very eyes.
Enemies unaware of your presence will suddenly turn around and sound an alarm as soon as you pull out a weapon (even the 'stealthy' piano-wire!). Other times they simply won't.
Pathfinding is chaotic at best - I've experienced situations where enemies that patrol have desynced their regular patterns with one another, to the point where it was literally impossible for me to remove one from the equation without another witnessing it.
For some reason, Agent 47 always massively prioritises stripping his victims over dragging them away.
Direct headshots don't always kill, even on enemies with no head protection.
Have fun climbing up to the top of a ladder and then falling through the earth into oblivion (and meeting instant death).
It is these problems that dampen the ahead-of-its-time concept from realising it's potential, and thus the game has not aged well, at all.
Even when eveything comes together for a mission, you know the next experience will be a crapshoot once again.
I cannot recommend this game. It is not fun, it is frustrating.