I won't write anything about the ending and while I am only going to suggest things, I still felt I should tag the spoiler box. The premise of the movie is pretty simple and for what it's worth anyone who has seen more than 4 thrillers will know where this is leading up to. It is so obvious that it might actually hurt. But the actors are really good in it and they make it worth while.
Of course if you never watched a movie like this and don't care about a movie's title than you might actually be surprised. But even without reading the description of the movie (never do that, so I won't be spoiled major developments in the movie) or anything about it, I could tell you after a couple of minutes where this was leading to. So no points for "surprising" ending/twist then. Also it's tough to really completely feel for that particular character, even though he transforms. It's very elaborate but he could/should still have seen through this.
Of course if you never watched a movie like this and don't care about a movie's title than you might actually be surprised. But even without reading the description of the movie (never do that, so I won't be spoiled major developments in the movie) or anything about it, I could tell you after a couple of minutes where this was leading to. So no points for "surprising" ending/twist then. Also it's tough to really completely feel for that particular character, even though he transforms. It's very elaborate but he could/should still have seen through this.