If you have a dark sense of humour....
You'll probably think it's a comedy masterpiece like I do. Good lord, I've seen this film with a few ...and some have been utterly horrified at some scenes, whilst others have almost broke their ribs with laughter. Case in point: the scene with the two old women where Cage loses it with them.
Don't get me wrong, it has it's dark and serious moments. But so much of it is very dry/black in the humour department. Coupled with Cage's EXPLOSIVE performance it makes Bad Lieutenant a future cult classic for me.