Things I liked: Nylon, stiff but completely safe for softer barrels like brass.
Things I would have changed: Might make them a little longer, but no complaints.
What others should know: These brushes work well, and also seem sturdy. I don't think they'll be falling apart any time soon. True, the nylon will probably wear a little faster than bronze bristles. It is softer, after all...but maybe that pliability means that the brush may actually last longer. I usually throw out my bronze brushes long before the bristles wear down, due to the fact that they bend, and get too loose in the bore to be of any use. I guess time will tell which one lasts longer.