These are very bright for other road users directly in front/behind you to see, and they're very compact and easy to take on and off - battery life also seems to be good, but my main problem with them is that if you go through a typical rainy ride you'll have to take them off, take out the batteries and let each seperate piece dry out before you use them again, as they regularly freak out and stop working when wet.
First dissapointment was the size. I probably should have checked somehow but they are VERY small. They are not bright enough to use as a torch however bright enough for other road users to see you. There is no indication as to how to install the batteries! In the end I figured out that you need a thin knife to wedge in the front end of the casing. For a small and easily adjustable light set that will allow other road users to see you, this is a great set.