There are several things about this light that make it very good. It's small, it has a good mounting (a band capable of fitting nearly anywhere you like), it runs for ages on two AA batteries, it's weatherproof, and it costs under £20.
For being seen, this is a great little unit, but it's not that great for seeing where you're going. Then again, it's clearly not intended for that kind of use. The first mode when turned on is flashing, making it legal, and the second mode is constant. By far the best aspect of this light is how visible it is from the side. The LEDs are quite far forward in the reflector, making it more noticeable because it's more than bright enough to attract attention. Of all the lights on test this is by far the best as regards visibility from obtuse angles.