Pros : I like that these are premixed. I experimented using them on different colors of glass and the colors show up best on white and black. They can be used watered down for a painterly look or full strength for stronger color. I use them along with Glassline and a transparent enamel and they are forgiving as far as the firing temperature.
Cons : I prefer Glassline black for details. The squeeze bottle is awkward and makes a thick line. I use a brush and toothpick to scrape the edges of my design.