Son of Sardar is a movie starring Ajay Devgan directed by Ashwani Dhir, known for his successful direction in Atithi Tum Kab Jaaoge and One Two Three. If you've watched any of these two movies, you know one thing. His movie doesn't really have plot but still does good on box-office because of its witty jokes and punches.
Similarly, SOS doesn't really have a plot(or at least a convincing one). But that's not why its rated 4. The reason is that there is nothing in the movie to sit though its agonizing 2 and half hour.
First half is good enough. With some jokes making you laugh. But it gets boring as the clock ticks by. A good joke looses its humor the second time.
I really had high hopes from the movie as earlier comedy movies of Ajay Devgan had been really good like Golmaal 3 or All The Best. But this is yet another Bol Bachachan. Both being the remakes of movie most must've watched before.
But its not all that bad. If you "loved" Bol Bachachan or One Two Three, give it a try.