I used this glue on the knots of some new leaders that I made and it is incredible. It is easy to apply as long as you are in shade and it hardens in seconds in the sunshine. Just avoid getting it on your fingers because it does not come off easily.
There isn't anything bad to say about this product. Loon UV Knot Sense is THE product to use for putting a protective coating over knots, especially fly fishing leaders and backing knots and whipped loop connectors. This isn't super glue, it's a UV cured polymer that cures rock hard (use the little UV lamp) and there is no substitute. Remember, it won't make a poorly tied or weak knot stronger, it just coats a knot so it doesn't hang in guides or loosen with repeated use. You'll appreaciate this when a bone fish gets you into your backing before you even realize you set the hook. Makes a good fly head coating but a little pricey for this in large quantities. I always keep it in my tackle bag along with the mini lamp.