I've used the HubBub helmet mirror for over 10 years, on day rides, week rides and a cross-country ride. The mirror is better than mirrors mounted on the handlebar or glasses frame. I've given it as a gift to friends, who enjoy it. I don't ride without it.
He signed it with love!
I love my hubbub mirrors. I bought 2 so I already have a spare. I think they should be mandatory :). Feel free to quote me.