I bought a large roll of that stuff. I have not used it much because it is really hard to see under a bright light. I saw a bike on the side of the road once with this, and it barely glowed. Practically speaking its about as bright as a white license plate. I don't find the black very useful. The white on the other hand can be blinding.

I've taken to just putting red on the inside of my front fork and chainstays. I like the look.

This bike was all black/grey. Now it has blue and red reflective striping.