I suppose I'm being a bit harsh on what is by all rights "just a thriller". Subsequently I suppose things'd be dandy if "Unknown" were at least some form of thrilling. I propose a new subgenre: twisters! The key reason to see any of these movies - even director Jaume Collet-Serra's last outing "The Orphan", for example - is to try and figure out the inevitable (and in this case, essentially promised) twist ending. Then, again, "Unknown" isn't the best platform for its fellow twisters to defect from as it fails to engage the mind. There are clues, all be them noncontextual, along with a clumsy tightrope act between rationality and insanity, but to boil it down is to realize the desired information isn't discoverable. It's simply withheld. Our twists come to us in the form of blatant, unrewarding exposition whenever the filmmakers deem it timely. At least in "Shutter Island", which features perhaps the most exposition-heavy twist reveal in cinema history (one character goes as far as to pull out a chart; 'nuff said), we're tugged to and fro throughout in spite of being 99% sure we've solved the mystery.
