There have been a few threads recently about these. Am really pleased with mine, can reach into zipped pockets/mesh pockets without removing it. I personally find it more comfortable than a Camelbak.
The weight distribution, ie on the hips, makes so much more sense. I have the largest size which takes a huge amount of stuff, could really do with a smaller one too.
My only criticism is that I can’t do up the chest strap cos it’s not comfy for a girlie!
Don’t forget that it doesn’t come with a bladder so it’s very expensive.
I gather that there is a long delivery time though.