Based on a true story by Zeishan Quadri, the film is set in Wasseypur, Jharkhand, known for gang war between between gangster Faheem Khan and businessman Sabir Alam over a scrap business.
It ran houseful in most parts when it opened Friday and footfalls are said to be increasing.
"Quite undoubtedly the moment of the day has been the film 'Gangs of Wasseypur' (GOW), which I have had the great privilege to see. Indian Cinema at its best, honest, stark and as painfully real as possible.
"For one that has been born and lived a major portion of his life in almost similar environment, or at least exposed to it to some degree, I found so much that I could well relate to. And that has led to the authenticity...," Big B wrote on his blog, Bigb.bigadda.com, praising the crime thriller.
"Anurag Kashyap has not done any fancy shot taking and allowed the visuals to flow as they would, were one to be living those circumstances in real time," he wrote.
The film is soaked in blood and revenge and has stellar performances by Manoj Bajpayee, Nawazuddin Siddiqui, Richa Chadha and Piyush Mishra.
The 69-year-old also praised the work of Manoj. They worked together in "Aks" and "Aarakshan".
Amitabh wrote: "Manoj Bajpayee in particular, and of all the artists right down to the smallest in capacity and presence, has been beautifully done. No one looked or performed out of place. They just did enough and that was effective enough."
"Importantly though, the film GOW touched and expanded on a topic that apart from the blood and gore and the violence educated us on a social issue which most of us may never have heard of. The disparities yes, on more social and moral levels, but also on a factor that concerns religion and the evil that exists within most of the polity even now about it.
"In all a glorious film and one that I would recommend strongly," he wrote.