The story is one of the best I've seen in an adventure game, if you don't mind horror.
The characters are actually fairly interesting, and the character interactions are great.
The atmosphere created by the art is a 10.

In any case I felt continually compelled to keep playing to see what was next. The story manages to tweak your emotions throughout, whether desperation to escape, trauma of some event, intrigue of some mystery, or just pure horror.

Some of the puzzles were too hard for me, I admit going to the walkthrough several times.
It is important to check william's diary (there is a right arrow to progress through it) for tips on puzzles to minimize having to do this. Yet there were plenty of difficult point and click type puzzles that I was able to do and were very enjoyable.

There is a bug where sound occasionally screeches at you, and rarely crashes.
(I had 3 crashes total, not bad for such a long and fantastic game)
Distracting, but not a game killer.

It is quite a long game, and very challenging. I was very glad I played, I won't forget it soon.
I wonder if Black circle II is any good?

Non-spoiler tips:

Right clicking can produce different results than left clicking!
As best I can tell, right click is a kind of "super search".
Left clicking might tell you that something isn't interesting, but right click might find something big!

Sometimes you cannot progress in the story until you exhaust all conversation options.

Objects which were not highlighted before, may become highlighted when they become useful as new information is learned! So you may need to scan areas you were sure had nothing interesting before.

Sometimes a character will tell you to "wait" while they figure out something. This is a frustrating game mechanic where you might have to zip all around the place before coming back to check if they are ready.

There is one point where it is possible to save your game where a decision you just made has already caused your doom. That means if you only have one save game, you just ruined your game and will have to start from the beginning! I feel I must micro spoil this one, it is an event where you fire a gun to escape. I recommend keeping at least two saves.

Overall, black mirror 1 and 2 were among the best and most memorable adventure games I have ever played.
Highly recommended. I had some problems with the latter half of BM 3.