I have to give a slight disclaimer: what I'm about to say isn't backed up by facts or experience. It's simply my own personal opinion. However, I AM going to back it up with arguments, so you'll have at least some reason to listen to it. You can decide for yourself whether or not it's helpful.
If you're a writer you've probably been told at least once to keep your audience in mind as you write. But if you're at all like me, you don't even know who your audience is much less what they want from your story. Sure, if you're writing for teens there are things you either would or would not do to your story, but what if you're just trying to write a story and don't care what age group reads it? When I was a kid I read a lot of grown-up books and now that I'm an adult I still read a lot of kids books, so trying to classify your "audience" would probably only serve to show you that people can't be put into a box.
It may sound hopelessly egotistical, but I think every writer should write for one person--himself. True, you're not going to be buying your own book (probably); you are not the one million buyers who will send your book to the top of the New York Times best sellers list. But there is one thing that makes you a great audience: you know what you like. You don't know what all your potential readers like or want. In fact, according to Steve Jobs, they don't know what they want either until you show it to them.
I'm not saying that you shouldn't get feedback from others. You definitely should. The problem is that other people don't know your story as well as you do so they don't know what it needs as well as you do. I've had friends who asked me for advice about their stories (which I was very happy to give), and who kindly took my advice. But when they showed me the revised story I discovered that it was much better the way they had it before I stuck my sticky fingers into it. My changes weren't what the story needed and I felt bad that I had wasted their time and effort.
Other people can be more objective than you about your story, but other people can't be the author of the story. Only you can be the author.
Besides, if you like your own story you know at least one person likes it. Making even one person happy is a noble cause.
You're probably thinking, "Sure, but I want to get published and that means selling at least the publisher on my book."
I agree. But the things that make you like a story are generally the things that make other people like it too. On the other hand, if you put in gratuitous violence or strong language in the mere hope of gaining readers, you will probably end up with a book nobody likes, not even you.
Definitely get a beta reader. Definitely listen to his advice. But keep in mind that he'll probably never love your story as much as you do. So write your story the way YOU want it to be written.