The light is bright and you can't argue with the price.
There are a couple of things that let it down. The battery pack doesn't stay put on the top of the cross-bar and slips underneath - not a major issue and I'm sure I'll find a way to fix this. The bigger problem is the poor connection between the light and the battery pack; it's just not secure enough and comes apart too easily. You would expect a kind of click as the two ends are joined but the two ends just slide together. Again, I'll have to think of a faff-free way to make this more secure.
People have commented on the rubber rings that fix the light to the handlebars as not being stable enough but mine stays there rock-solid.