Really nice strap! I walked around all day with my new Canon EF 100-400 II telephoto lens and didn't have any neck pain. My heavy combination of telephoto lens and camera with battery grip didn't feel heavy at all.
I felt my shoulder a little, but being able to switch from left to right shoulder is handy for me. I'm right-handed, but wearing it the other way around wouldn't be a problem.
I'm a bit worried about scratching the lens/camera because of the metal parts. That's why I remove the strap and put it in my camera bag, in a separate compartment from my camera and lens. Works great. I just kept the strap on in case I wanted to grab my camera again. It also saves the hassle of putting it back on when your camera and lens are already attached :P That's why I took off one star for ease of use.
It's a shame they only come in boring black :P I do like a bit of color.