I've got two pair of them (Side note: I got one at a swap meet for $20, and the other was on a bike I got used. I probably wouldn't pay full price for them, because it's like $60 or so and for that price I'll get some "see!" lights anyways.)

They're pretty nice. Definitely "be seen" rather than "see" lights, but not too bad. Easy to install, but low to the ground (unless you get this new model, that I don't have.)

I had one light stop working. I emailed them, and they send me a replacement with no fuss whatsoever. Didn't even want the old light.