Pros : For the price, the assortment of colors is great. I have been using these for several years now, and have made some beautiful pieces. As far as the COE, these don't have one and can be used on any glass.
Cons : As with all enamels, you have to keep a water supply handy as they dry quick, and it makes it difficult to keep a smooth line.
Other Thoughts : As with everything, trial and error is the way to go. Do some experimenting on small pieces of glass by making sample strips. This way you will have the colors and know how to use them. If you make your sample strips on clear, all you have to do is lay the clear strip on top of the color you want to put it on to know if it will be the right color.