seems great, and well built. A little chunkier than some you'll find in stores but much more servicable.
Light housing, LED and reflector are excellent, but electronics are sub-par and could burn out if the bike is ridden too fast. See schematic: zener diode D14 should be switched with D? for correct operation. For brighter and more efficient operation use a full bridge rectifier into a 470u capacitor across the input of a small buck converter, and connect + to AC1 and - to AC2 as per the schematic. Then remove R1, R4, D1, D14, D15, D16, D17 and D?, and replace R1, R4, D15, D16 with 0 ohm links. This feeds the output of the buck converter straight into the capacitors on the board, and powers the LED driver directly.