That's a very fine piece of animation! You should surely make a finished animation, I really want to see your skills in action.
"I understood though that Newgrounds' users usually prefer long, badly-drawn but funny/silly/brutal animations, so I think I'll try to make one soon just to test it out."
That's not true at all. There's a variety of users who likes a variety of content. There's people who likes bad drawn while there's the ones who like animations where it has put a lot of effort (Though I think everyone likes good drawn animations = P).
And there's people who like funny, silly and brutal animations, as they like musical, romantic and adventurous animations as well.
What really decide if they like or not depend on their likes and dislikes, and the effort you put on your work.
Good luck on the next animation!