In Woocommerce, I am trying to get product custom attribute values but I fail miserably and I don't get anything.

So I tried:

global $woocommerce, $post, $product;
$res = get_post_meta($product->id);
print_r(unserialize($res['_product_attributes'][0]));

And I'm getting this raw data:

[pa_koostis] => Array
        (
            [name] => pa_koostis
            [value] => 
            [position] => 0
            [is_visible] => 1
            [is_variation] => 0
            [is_taxonomy] => 1
        )

I know that there is a value because it is shown in the attribute section, but I just can't find a way to get it displayed with my custom code.