There are two, maybe three villains in this story. Brian's father Murry Wilson is the bad guy in the 1960's. He was an abusive father to all three Wilson brothers, Brian, Dennis and Carl, but Brian was the oldest and most talented so he took the brunt of the abuse. He was also the most sensitive so the abuse affected him the most and it stuck with him the longest. Murry was the Beach Boys first manager and tried to control every aspect of the group. He was eventually fired but retained part ownership of their publishing company. After being fired, he sold the Beach Boys song catalog and pocketed the money. Even after that Brian was always seeking Murry's approval, which he never got.
The 1980's bad guy is Dr. Eugene Landy, an unconventional psychotherapist, who completely controlled Brian's life fo a few years. He imposed a 24/7 treatment program for Brian's addictions and mental illness. It included numerous staff members, unorthodox methods and mass quantities of drugs. He charged exorbitant fees for his services and used his influence to horn into Brian's music ventures. Landy also had a book written about Brian that Wilson has since said is mostly BS. In it Landry comes off as the great savior. He was eventually barred from practicing in California. There were also restraining orders barring Landy from having any contact with Wilson.
Mike Love, Beach Boy and cousin of the Wilsons, also comes off as an ass. In fact, he is an ass in real life. He was against any growth in the group's music and just wanted to repeat the formula from their early hits about cars and surfing.
There has to be a hero in this tale and it is Melinda Ledbetter who became Brian's girlfriend and eventually his wife. In the movie, she almost single-handedly saved Wilson from Dr. Landy. Amazingly, Melinda was deeply involved in the film's production. I have read much about Brian Wilson and the Beach Boys. While Ledbetter played a part in Wilson breaking away from Landy, she was not the main driver. That was mostly the work of brother Carl Wilson.
Other than Mike Love, the rest of the Beach Boys were barely in the movie. Several other key players during the 1960's are also ignored. That is probably alright since this picture is about how Brian got so screwed up and how he eventually recovered enough to function once again. It is by no means a comprehensive biography of Brian's life.
I thought Paul Dano was good as the young Brian. Paul Giamatti was OK as evil Dr. Landry but there were no shades of gray in his performance. Landry was portrayed as a 100% dick, not 99%, 100%. Giamatti also had a bad wig. John Cusack was fair as the older Brian but wasn't convincing to me. That is probably more due to my familiarity of the subject. The star of the show was Elizabeth Banks as Melinda Ledbetter. She was absolutely radiant on the screen. The character as written was a little too good to be true and the facts were twisted somewhat, but that didn't matter. Other than these four actors, hardly anyone else had significant screen time.
There were times when the switching from the 60's to the 80's was somewhat jarring and maybe not appropriate. I wanted to see a few more minutes of certain scenes, but then the switch occurred.
As mentioned, I have read fairly extensively about the Beach Boys in general and Brian Wilson in particular. Because of that, I came into this movie with many preconceived notions. That being said, I still enjoyed it. Of course, there is always the great Brian Wilson music for the soundtrack. I think it may be even more enjoyable for those less familiar with the real story.