As a tail light, this is not anywhere near as bright as some of the better rechargeables that have come out in recent years. It's sufficient for night time riding, but not bright enough to be easily noticeable in bright sunlight.
The radar feature, however, is compelling. With my Garmin Edge 1000 (I think it is compatible with several other Edge units as well), I get an audible warning when something is approaching from the rear, as well as a visual indication how fast they are approaching. This makes it very easy to glance in my rear view mirror to see if I need to move over. It can be pretty frightening when a car passes a little too close and you didn't even know they were there. If I'm riding fairly fast with a lot of wind noise, this happens to me more often than I'd like (at least before I got this Garmin unit).
It's also helpful for your riding buddies since they can easily see the light flashing as a vehicle approaches.
I'm new to road bikes and this is the light that was recommended to me. It is easy to mount and dismount and charging is simple and sure. There is an indicator light to tell you how much charge is left and the USB connection is easily accessed. I got about 2 hours at full brightness then my light began to flash so I changed it to low and had another half hour until it started flashing again. It feels tough and has performed well after three weeks of daily use. I'd buy it again.
This is a great addition to a commuting setup. I have a dynohub with bike mounted always-on front and tail lights. I put this L&M Vision 360 on my helmet. The bike mounted lights help me see the road and the Vis 360 helps drivers see me. This was very easy to securely mount on my Specialized helmet and I barely notice the additional weight.
The important thing to note is that the Vision 360 does NOT flash, it only pulses. This was a surprise to me, especially after watching some product videos - the light does not flash like that anymore. Per L&M, they changed to pulsing in order to comply with EU regulations. L&M also believes that pulsing is less distracting for car drivers and it limits fixation on the light. At any rate, it's still a great light so please be aware of this and set your expectations accordingly.