What does non-tempered couverture chocolate taste like?
Couverture chocolate is generally used in coating and molding because it has such a nice sheen due to its high cocoa butter content. It's usually very high quality and so should taste very good straight out of the bag, although the texture will be more creamy than non couverture chocolates.

Couverture is not better than other high quality chocolate, just for a specific application. You won't find much chocolate candy made from it, that's not because the chocolate isn't good stuff, it simply that the effect the makers intend requires a lower level of cocoa butter. 

As for how to tell good quality chocolate from poor quality the best way to tell is to taste it.