I don't know if the movie really was shot only in one (long) take or not. I know that it has been done before, "Russian Arc" being one of the most elaborate movies to have done so (though I haven't seen that one yet). The question is, if this is more than just an experiment? And isn't it better to cut away to something else sometimes?
The story is pretty straightforward (no pun intended) and might not give away were it is going from the get-go, but if you follow it (again with the pun), it will eventually become very clear, what lies behind those walls. Of course if you have seen a genre movie like this, you might be on to where it is actually heading. I can't tell you how much less you will enjoy the movie, if you come up with the solution, before it is revealed. I can tell you, that for a "single-take" movie it does and sounds pretty good though
The story is pretty straightforward (no pun intended) and might not give away were it is going from the get-go, but if you follow it (again with the pun), it will eventually become very clear, what lies behind those walls. Of course if you have seen a genre movie like this, you might be on to where it is actually heading. I can't tell you how much less you will enjoy the movie, if you come up with the solution, before it is revealed. I can tell you, that for a "single-take" movie it does and sounds pretty good though