I have been using it to zendoodle. Here is the piece as it's drying. I used Fine Line Resist Pen 0.5. It dries quickly and the only issue is hand control and pressure given while you draw.
Once the masking fluid is completely dry I use watercolors to fill in the open spots. You must allow the watercolors to fully dry before attempting to rub off the masking fluid. I found that the heat gun speeds up the process. Rubbing the masking fluid off is simple, however do it gently and not to fast. If for some reason an area has not completely dried you are liable to have the masking fluid tear up the paper.
This doodle has been done for weeks but today I finally got around to coloring it.
I was excited about trying a bigger piece that I started and completed this one this afternoon.