If "not seeing it coming" is your decisive criterion for which thriller to watch, then go ahead and watch it. Some say the twists were way too obvious whereas others say the twists were realistically smart. I, therefore, cannot tell what is in store for you.
If not, then carry on reading: I do not appreciate a movie that tries too hard to surprise and does that without a story. That keeps me asking "so what"? Personally, I didn't find the twists as realistic as some deem it to be, as realism, to me, has more to do with the tangibility of causes than the nature of effects.
Once I had realized the movie was all about twists rather than the story, I stopped caring about how the story told in flashbacks would unfold (because a partially hidden retrospection is what these movies are all about, most of the time).
So, there actually is a story, but the story pertains in the twists and I was expecting otherwise. It almost feels like the movie is saying to the viewer: "I want to surprise you so much that it is actually impossible for me to think of a captivating story with believable motives, see, a movie can only last this long and because I am filled up with twists, I cannot even build characters and back up my story, there is in fact no story even though it might seem otherwise, because there was no time to give you one." This is the single reason I rated this movie a 5. It is interesting enough to keep watching with an anticipation to see more of what is coming and then letting it all add up coherently, but, in the end, all I felt was that I didn't even care about what I had just seen. I couldn't find a single thing worthy of remembering in this movie.
Other than that... I liked the performances of the actors. I found the setting to be a little too nondescript for my taste; with nothing really sticking out in particular and setting a memorable atmosphere. Maybe I should have chopped more off the rating because of that.
