This is my first power measurement device and I've been very impressed with how easy it is to use. I connected it to my Garmin and it has worked flawlessly for the past year. I find it particularly useful for long hard rides to optimize my pace without burning myself out.
I got this to replace my Garmin Vector 2 pedals. They work, but the Quarq is a simpler, more user friendly power meter. Once it is installed it is easy to set up and use, and it always seems to work without any drama. I have come to depend on the power meter to make sure I am training in the right zones. It also helps me pace myself up hard climbs and during races.