I think it depends, it looks good on some people and not so good on others.

If you're comfortable with it, don't do anything with them. I like thick eyebrows, by the way.
If you do want to fix them, imo it's best to visit a beauty salon, they'll know what will look good on you and will do it properly. I've seen many people who wanted to fix their eyebrows for themselves and the result was tragic.
