The article linked from the question mentions several benefits of coconut water, such as high mineral content, antioxidant activity, preventative effect against diabetes, kidney stones and high cholesterol levels. It is clearly said in the article that the evidence comes from animal studies and that they haven't found any human studies that would confirm those results.
They mention a small and short human study (28 participants, 4 weeks) in which coconut water was associated with a decrease of blood pressure.
They link to two small studies (8 and 10 participants) in which the hydration status was not significantly different after drinking coconut water, a carbohydrate drink or plain water.
The search site:gov "coconut water" "systematic review" gives almost no relevant results, which suggests that very little research has been done about the effects of coconut water on human health.
One cup of coconut water can contain 400-600 mg of potassium (USDA: here and here), but a single serving of beans, potatoes, banana or other foods can provide more. Coconut water contains only a relatively small amount of other minerals and vitamins.
In conclusion, there seems to be no convincing evidence to say that drinking coconut water results in any specific health benefits or that it contains nutrients that couldn't be obtained from a variety of other foods.