The markers do seem to leech into the paper, meaning if you apply the marker to dry paper you can never completely wash away a mark, you might see a line of pigment even after washing most of it away, but being aware of that just made me use it to my advantage.
The main drawback to this set has to be the variety. I usually ended up only using the green and blue markers. The yellow and orange are extremely similar to one another and the red is under saturated, making it turn out pink. The black is, well, black. I guess I could mess around with it for shading and maybe even inking, but I just prefer ink for that, not watercolor.