You Don't Like This, But I Do

I love salt & vinegar chips, but my sister can't stand them.
I adore Rhett Butler, but my friend thinks he's deplorable (she's an Ashley fan).
I think kneeling during the national anthem is childish and disrespectful, but plenty of people support the "men" in football uniforms who do.
Suffice to say, we're all different. We have different opinions, tastes, and preferences. Especially when it comes to books.

Give your novel to three people and you might get three different responses, varying between:
"I LOVED it! Don't change a thing."
"You need to have more (insert genre) elements in your story."
"This just wasn't for me."
The writing industry is so subjective that it becomes impossible to know what opinion to trust (though if more than one person is telling you something about your story, you should definitely take their suggestion into consideration). When it comes down to it, there's only one person you can really trust.
Yourself.
All writers have a certain instinct that tells them when something they've written is worth keeping...or needs some tweaking.
I'm not talking about when you're in the euphoria of writing when everything is ahh-mazing (or horrendous). But when your brain is permanently fixed in editing mode.
So, if you get some feedback you're not sure about, sit back and think. Decide if, based on the opinion at hand, you believe a certain scene, dialog, sentence, etc.  needs to be fixed.
And then proceed from there.