Originally Posted by MichaelW

If you use quality LED style headlamp eg Busch and Muller, then you should find it sufficient. You can always add an additional lamp if you feel underlight. I ride on normal city roads and some dark paths and find it plenty.
The optics are bike-specific so you get a concentrated rectangle rather than a generic circle of illumination.
With LED you should really use a rear lamp but they work OK without.
I use the higher grade Shimano dynohub (with disk brake) and its a great piece of kit.