This is much better than the OEM Canon rubbish that came with my 550D. It feels much more natural to carry the camera by my side, and it doesn't stick out in front of my stomach like some kind of alien protrusion. I'm a little worried about the plastic buckles supporting £1k's worth of kit, but I guess it's been tested and everyone else on the forums say it's OK.
The big flaw for me is that the straps get in the way when shooting in portrait - it's not a big deal but with a bit of thought it could have been designed out.
It would also feel more natural to me for the camera to hang by my left side (I'm right handed) so I could reach across and grab the grip with my right hand. When it's hanging on your right, you have to almost reach backwards and take your eye off the subject. Might be just me though....
All in all, a good buy, and cheaper than the competition (though still a lot of money for a bit of webbing and a couple of buckles.