Its an entire MMA based film. From Vidyut to all enemies, they all know MMA and its a treat to watch the action. Full marks there.
Story wise, it is quite similar to Die Hard with definite variations. Story has nothing to be talked about its only the action that is to be talked about throughout.
Yes, it has some weird moments like there is one sequence (I wont tell you which one but you can figure it out) which will instantly remind you of a sequence from ROBOT (2010) where Chitti, while fighting goons in a train runs out of battery and seems out of the battle but soon comes back after somehow managing to charge his batteries...watch out for a similar sequence in Sanak.
Performance - Hated Rukmini's presence in this film. Its an out an out Vidyut Jammwal film and it belongs to him for his splendid action scenes and performance. Police including Neha Dhupia has absolutely nothing to do. What will they do? Their work is done by Vidyut xD. Chandan Roy brings some good humor to the film. The bad guys have done a good job too with their MMA skills too.
Overall, a decent one time watch. Watch it only for the action (Just like Extraction --> 0 story, 100% action) and for Vidyut. Dont expect twists and turns in this linear storyline which was a disappointment for me cuz i am not a fan of all and all action films with a story that is one directionally moving. Bollywood should take inspiration from films like these and level up their action sequences.