I bought this helmet a couple of weeks ago for climbing and I love it. I ordered a M/L and I probably should have ordered a S/M. I'm an average sized lady (5'4", 130lbs) with a medium sized head. However, with the adjustable head rachet, I can tighten it up enough so that it's not useless! But I would suggest measuring your cranium before ordering...
My favorite feature is the head lamp clip! And let us not forget that it's ultra light!
I haven't taken any solid hits to the head with it on (and let's hope I never do).