Open ends

Are open ends a good way to do endings?
Or do they leave your brain racking on top of itself.

Selena Gomez has no help to this matter.

I finished watching an anime. It was called Monster and the show was so brilliant.
Could you argue that the ending was great?
I just think it was left for the viewer to decipher.
There was so much mystery surrounding Monster and the way it ended you have to question a lot.

I mean it is symbolically and philosophically deep.

What is in an open ending. It is the viewer's interpretation.
I mean that's what makes it amazing.

I was talking with someone at a networking event. They told me everything is subjective. In essence, this can't be true.
There has to be objectivity at some level. Therefore, sure the ending is subjugated to subjectivity but what did the author intend? The only way to glean anything like that is to really seek out the previous works he did.
You see Monster was adapted from a manga. So, the anime for was adapted good and proper.
And yet we trapes back to the ending.
What does it all mean?
I can't say without spoiling what I think it means.
For now it was very open ending and it wasn't abrupt like a head scratcher.