The Problem With Helmet Mirrors
In the absence of an alternative, helmet mirrors are definitely better than no mirror at all. The idea is great, but on the road, they only function well when your head is in a particular position. Whatever position you last aimed the mirror in, that's the position you must have your head in order to see behind your bike. They do let you see behind your head, but in the fast pace of the road, finding that correct position to see behind your bike usually takes more time than you have.
Helmet mirrors also come out of adjustment frequently, so you find yourself fussing with it instead of just riding and being able to rely on a mirror that's always in the correct position.
Helmet mirrors also have a blind spot. When you're riding and looking straight ahead, the mirror is positioned on the traffic side of your field of view. You can see whatever image is in the mirror, but you can't see what's on the other side of the mirror.
A lot of well ventilated helmets these days don't have a great place to adhere a helmet mirror to, so they end up not being securely attached to your helmet.
The other complaint we hear so often is that helmet mirrors look dorky. That's for you to decide, but we're sure you'll find the Italian Road Bike Mirror to be a component you'll be proud to have on your bike.