I won't lie – when I first tried writing with these pens, I was really turned off by how they felt. It's so different than anything I've tried. Most pens have a very firm tip that allows you to write in a very controlled way. Brush pens offer a different kind of control. You just need to back off a little.
Brush pens write the way they do because of a cluster of tiny fibers that form the tip. Since there's hundreds (thousands?) of these fibers in a cluster, you get a beautiful variation of line widths and ink flow. I would compare it to a flex nib, but I don't own one to compare it with.
After figuring out to press lightly and limit my upstrokes, I began to really enjoy writing with the pens.
These aren't pens that I would use to write for long periods of time. I've mostly used them to jot down notes and (more often) draw quick doodles. These pens are fun to play with, and that's a good enough reason to have a few. They're fun.