With the Take-A-Look it's very easy to keep track of traffic behind you. It's the closest experience to a rear view car mirror I've ever experienced with bike mirrors. Part of my ride includes a short blast at 25+mph taking the lane on a busy street and the Take-A-Look works flawlessly in that scenario. Biggest downside is the geek factor. In probably 10k+ miles I can only think of one time the Take-A-Look blocked my view enough to cause an issue (and that was another cyclist pulling out from a cross street, not a car.)