This movie has it's strong points and weak points. I'll split the movie in 4 halves rating each with it's own rating.
The first half's start was okay but then it felt weak and then it picked up pace as it moved on. I'd rate the first half a 6 or 7/10 as it had many cliched parts plus some valuable ones which got me intrigued
The second half started really strong and loved the social message that was delivered and the way it answered questions from the first part but then it started to fall apart in the end where they went for more of a cliched action climax than delivering a message. Don't get me wrong, they do deliver the message in the end but the final climax wasn't all that upto the mark in my opinion. I'd rate the second half a 7/10 just because of the really strong start.
Overall this movie would be a 6 or 7/10 depending on how you view it. There sure are many memorable moments and some that doesn't make any sense. If you're into sci-fi and rajini fan, watch it.