I came in with high hopes given he was up for an Oscar for this role. All in all though, I came out pretty unimpressed. He certainly gave a realistic portrayal of an alcoholic. There were a couple scenes with a bit of emotion to them. Other than that though, it just seemed to be him plotting along at different levels of obvious self destruction.
It's certainly possible they didn't give him a chance to do any more with the character but there's many other Denzel movies I liked him in more.