You don't have to like movies for them to have been good! You could despise a character while still thinking the movie was good for making you despise the character. That's an art.
If they have a strong emotional impact on you, they've "worked" (other than if they're just crap) because you talk about them, digest them and question their messages. A ton of great movies explore the darker side of humanity by using despicable characters; that's the beauty of story.
Just because a movie evokes a strong emotional impact doesn't make it good. A strong emotional response can be highly negative as well.
If the movie is made to create a negative emotional response then I suppose one can say it succeeded in doing so, but it still doesn't make it good to the people who view it negatively.
However, most (good) movies do have a lingering message, a thesis point the filmmaker is trying to make about people or the world. What do you think the message was in this movie, and do you agree with it?
It's a while since I watched it but I guess it's about the length some teachers will go to if they want the legacy of being the teacher of a great musician. It's about a nasty, revengeful, obsessive character who will stop at nothing to separate the wheat from the chaff to uncover a diamond or to screw over his enemies.
I don't think there's anything to agree with in terms of message since I didn't see in it any condoning of Fletcher's behaviour. Sure, in the end his approach did uncover greatness, but through seeing the toll it took on Neiman, I certainly wouldn't say the film advocates that that is how music should be taught. I also wouldn't say it contained a warning either.
There are several possible messages you could read into the movie, and that lends it depth.
You don't have to like movies for them to have been good! You could despise a character while still thinking the movie was good for making you despise the character. That's an art.
If they have a strong emotional impact on you, they've "worked" (other than if they're just crap) because you talk about them, digest them and question their messages. A ton of great movies explore the darker side of humanity by using despicable characters; that's the beauty of story.