Pros - they cost less than 1/2 what Copics cost.
they seem to last forever - I have had mine for more than a year and use them almost every day.
the sets frequently go on sale, and are more than adequate for most card makers/crafters.
I like the tips, the fine tip easily colors small spaces and I doodle with it as well and the wide end is great for coloring big spaces. They blend well and if you remember to color in a circular pattern, you shouldn't have any problem with streaking.