Honestly, think the movie is definitely worth a watch. Keeps you interested with the plot essentially for the whole time and it definitely has a better plot than a lot of thrillers these days. It's not as bad as I heard it was but, the issues with the film do leave you wondering "How?".... as in how could these have possibly made sense? SPOILERS AHEAD
With the ending as it was, obliviously a few problems arise immediately.
1.( Of Course) How else did they expect a man to react after seeing all his friends die???... Including watching his girlfriend die right in his face. Of course he killed the man in cold blood whom he thought was the cause of all his friends deaths.
2. How could you plan such a conniving prank, with the assumption that he solves literally every puzzle correctly? I'm not 100% sure a gear would've came to mind as I was thinking about how to save my girlfriend from drowning. Could it have ended there .... And what type of safety net is implemented in that situation just in case he didn't figure it out??? What would've happened if he drove away to get help or even never decided to escape in the first place? He could've given up and accepted defeat.
3. I could maybe forgive 2..... But if everything went perfectly and he didn't kill someone at the end..... Severely traumatizing someone for a prank is a bit Overkill. I'm fairly confident, they succeeded in their jobs before the 2nd part had even started. Even if the kidnapping had just been a means of transportation to the celebratory gathering.... It could've ended right there.
4. Finally, I kind of figured they might go the 'it was all a ruse' route once I saw Thomas die because it was comical. I mean, the Russian guy WITH A GUN.... Decides to charge them while shooting all of his shots into nothing and immediately tackling Thomas into the elevator shaft. Could've had Thomas maybe sacrifice himself as the Russian guy walked towards them and potentially grab him and pull him in the elevator shaft to save his friend ...IDK. Anything other than what actually happened..... But maybe I'm just nit picking.
Anyways.....seems like a few plot holes that you get because of the ending......because without the ending the way it was, it might have even been a great movie to be honest. The ending basically undercuts everything that already happened to give you a moment where you feel for the main character and understand where he's coming from.... But that's it! You don't understand why anyone would do this to their FRIEND and it makes you question too many other things. Oh well....I still decided to give it 4 stars because I did enjoy watching... Maybe actually would give it a 3.5.