I liked Depp's interpretation of Whitey.
For those who know Billy Bulger Cumberbatch didn't capture the real Bulger. He replaced Guy Pearce who had to back out at the last minute because of scheduling conflicts. To be fair he didn't have adequate time to prepare.
Billy Bulger is a legendary wit. His role as master of ceremonies of the annual St. Patrick's Day Breakfast over a period of 30 odd years was a showplace for that wit. There are youtube clips.
Cumberbatch didn't capture that wit at all.
In the movie Billy Bulger's use of profanity in private does not not ring true to me.
All that aside the movie might offend Boston accent purists or Billy Bulger purists but I liked the movie.
I can get past my problems with Cumberbatch to appreciate that the movie will reach a larger audience who don't care about the accuracy of the portrayal. In that context I can appreciate the conflict of the Senate president aware of his brother's reputation being loyal to family while wanting to keep a distance from his brother's activities.
This is a compelling movie about a complex web of crime and deceit that gripped Boston for years.
Here's Kevin Weeks on Billy:
Interviewer:
The relationship between Whitey and his brother Billy has always fascinated me?that the most notorious crime boss in Boston could have a brother who, as president of the Massachusetts State Senate, was the most powerful politician in Massachusetts.
Weeks:
OK, I was up at Billy Bulger?s house over 100 times with Jimmy. He never discussed any street business or crime with Billy. It was always conversations about regular family stuff. There?s no doubt in my mind that Billy knew Jimmy was involved in the rackets, but as far as the murders, if Billy did hear something about that I bet he?d choose not to believe it, because he?s a very religious man. There was the case of Senator John E. Powers, who was a judge. He fired Whitey from being a janitor at the courthouse. Billy never forgave him for that because after Whitey was fired from that job, he started committing all these crimes and stuff. So when it came to John E. Powers getting a raise or anything like that, it never made it past Billy Bulger in the Senate. So if someone was attacking his family, sure, he would stick it to that person whatever way he could legally. But as far as shielding Whitey from investigations? Billy never did that. Never.
The joke around Boston at that time was that Judge Powers' office was moved into a broom closet.
http://www.thedailybeast.com/articles/2015/09/20/whitey-bulger-s-enforcer-slams-black-mass-the-movie-is-pure-fiction.html