So, as this game seems to be praised by everyone, I finally decided to check it out. It is hard to give a review about this game without spoilers, so read with care. It starts with a scene that let's you think you are a tourist, but the player will very soon be taught better.
In the first part of the game two kinds of scenes take turn -- the protagonist tries to retrace what he previously did, and if there is something deviant from the actions that happened before the actual gameplay, the gameplay will move to an interrogation room where the player is told why it cannot have happened like he tried it. These interludes are helpful, they give hints what to do. The player has to work with certain gadgets found in the inventory. It is fine to experiment with them -- if something is not correct, the game will switch to the interrogation, and the situation can be replayed. The conversational system is quite simplified and reminds of a platonic dialogue: the player can only confirm or negate the questions of the interrogator. It is easy, but sufficient.
It all changed for me when the protagonist's life was at stake for the first time. I had read some comments before, it had been inevitable; and there had been remarks that the game contains one outstanding puzzle -- and there it was. Thinking about actions that might have effect -- no matter how likely they would succeed -- I tried something, and then something happened that changed my whole point of view about the situation. Yes, the voices had been right. This puzzle is one of the best I have ever encountered. It is perfectly integrated into the storyline.
It is advisable to save the game frequently during the second part, especially in the end game. There are tough situations and the player has a hard time not making a mistake. These moments come very close to what we call stealth action, in a text-based version -- it is excellently managed to convey a feeling of being pursued and trying to evade from the scene. The second part may be a bit tedious, because the puzzle conjoining the parts has too much of an actual climax. But it still fits the frame.
So, what is the conclusion? The game may be a bit too tough for beginners, but everyone who likes interactive fiction has to play it sooner or later. This is a masterpiece.