This a good light to be seen, but not to see in dark conditions. It has a 180-degree view, but the light isn't focused so you can't use it for night riding. That's fine as I bought this to be seen. The only criticism I have is the battery. As it's winter, I haven't used this on a long ride, but it seems like 5-6 hours is the max battery life on even lower setting. It also takes a long time to charge. So don't use it at night and don't expect it to last on a long ride and it's fine.
Coming from separate Cycliq Fly6 (commuter) and Garmin's radar/light (road) units I find the 715 a decent but slightly flawed upgrade for both my commuter and road bikes.
Garmin's radar is something I wish I had sprung for long ago, naively believing that my dorky looking but very functional (Take a Look) helmet mounted mirror was good enough. Still keeping a mirror on my helmets because nothing beats visual confirmation of what's behind me, especially with some of the more 'gifted' individuals given a license. The radar combined with a Garmin head unit (1040 and now the sweeter 1050!) just makes me feel safer. Functionally, the 715 radar works almost seamlessly, save for occasionally having sensor communication issues (Bluetooth or ANT+?) with the head unit du jour. The connection usually pops right back after a few nagging beeps and has yet to do so during alerts.
The camera portion is the flawed part, alas. No image stabilization is the real head scratcher from Garmin, given their otherwise well designed Edge and radar only Varia models, especially after years of iterations to get them right. Heck, I still run 10 year old Virb cameras on the front of my commuter that have stabilization! I bought this for safety (mostly so my widow has something to try and get compensation from whomever takes me out), not to record my epic commute, so I didn't expect action camera level. If I want that I'll get a dedicated action camera, and it sure isn't going to be rear facing. The lack of stabilization is something even Cycliq offers on their Fly6 models, at least of late. I have several older Fly6 models I used for safety, but they were never up to Garmin level build or support. One other nitpick with the 715 is that the lens material appears to be plastic or very soft glass, and there are reports of it easily scratching. I was able to find glass lens protectors from brotech that fit it, however getting them shipped to the US is problematic.
The 715 has flaws that make the additional cost questionable but worth it to me, given I get one rear device with lights, radar, and safety camera.
I ride a race bike on semi-rural roads in Northern California and use a both flashing taillight and small rear view mirror attached to my glasses. Occasionally oncoming cars will enter my lane to pass and it's clear they either don't see me or don't care that I'm there. This light addresses the former drivers. It is quite bright even in sunlight. It is also small and virtually weightless. My mirror saved my life once, so I am aware that there are.both homicidal as well as distracted drivers out there. This light helps minimize the threat from the latter.
I've been road riding with one of these for close to 20,000 miles and it has been nearly flawless. I ride a mix of city streets, county highways, and desert single lane roads. The radar gives me a much better sense of surrounding traffic than would a combination of hearing and head-turning. False-positives are rare and seem to happen when turning right at intersections. Missed cars are extremely rare, but the RTL515 is still not a substitute for looking over your shoulder when changing lanes or passing parked vehicles.
I'm using the RTL515 with a Garmin 530 Edge unit. The dot and colored band on the side of the screen works well and is easy to see in your periphery vision or a quick glance down. It's not like you're reading a number or deciphering data to see that a car is gaining on you. It's simple and safe.
My RTL515 is a few years old, but as far as I can tell it still uses a USB Micro cable. This is literally my only gripe. USB-C is easier to use and should last longer.
