Just as bright as a 35W BA20D bulb, no more, no less. The yellow light is good for safety, it is better in foggy weather, and it makes you more visible in traffic (if your local traffic laws don't rule "white light only" or "yellow light only"). As for any LED lights, the roadsigns appear brighter. I use it for more than one month, and I'm happy with it.
Works well, colour is warmer than halogen, more incandescent not too yellow