The tapered point retains its pointy shape. The ink flows well and dries quickly. By holding the pen brush lightly, you get fine lines and larger ones with a slight pressure. The calligraphic feel is interesting.
As I started a new small oil painting on canvas board, I wondered if I could use the Pentel Color Brush for the initial drawing. I gave it a try and it worked well. Because the bristles of the nylon tip are springy, the texture of the canvas is not an issue. The ink goes smoothly from the cartridge to the tip of the brush and it was easy to draw on the vertical support: The ink did not drip and I did not have to squeeze the cartridge once.
On a second painting I started, I was not happy with the scale of one of the figures in the composition. I just took a rag and wiped out the drawing to start again. This left some marks, but nothing that went in the way.
The ink is not permanent (I could not find any indication about the lightfastness of the ink), but the interference with the paint was minimal, even with the steel blue colour that is quite strong.