Set in Bihar, the characters are all fictitious (yeah, wink wink). Personally, I thought Shool was far better as a film and far more effective in telling the story it set out to tell. Gangaajal just has so many deviations that while trying to fit them all in, the director runs out of steam and seems to lose track of the main story. For the most part, you have this vague feeling that something's happening but can't really put your finger on what's the point of what's happening onscreen. There is gratuitous violence and more than enough colorful language to keep the audience morbidly interested.
Ajay Devgan is quite good, but he seems to have done this movie on his breaks from
Qayamat - an SP with hair stylishly dyed brown?? He also smokes way too much onscreen, and needs to change his stance and urgently seek the services of a top notch dentist. Mukesh Tiwari, Mohan Joshi and Yashpal Sharma all do really well. Gracy Singh is just there to be the cop's wife - we all know what that means in terms of a role, right?
Gangaajal was never meant to be an entertainer. In its genre, however, it's a decent film, albeit not classic material. Serious, brooding and pretty violent that it is, I'd say have a really light meal (if you must) and prepare to get cleansed, one way or the other!