For weight loss it's good, especially if you use it in place of other fats in your diets. They are gobbled up by your body for the health of various organs in your body, and as an energy nutrient they are readily available for us (unlike saturated or trans-fats).
A deficiency of the fats found in fish oil are linked to a number of disorders. I'm not sure that eyesight is one of them -- for improved eyesight I'd recommend lutein.
