I just affixed this on my old G23 carry piece. I fell in love with the idea since I didn't want to take off my grip cover and lack a front rail to mount anything on. Plus, the guide rod lasers cost twice as much!
the indicator light (not an LED, it's actually a little bit of the laser light redirected to be visible) is not as bad as people make it out to be, even in low light it's no worse than aiming past the hallway night light.
ambientweather.com has it for ~$150, and I managed to get it for $158 after tax at my shooting range by mentioning that.