I don't go on a rifle hunt without one. It does take a bit of practice to get the adjustments down, but now that I've got that figured it's great. I only use the shoulder strap when actually hunting and mount it on the side of the pack (as shown above on the horseback sheep hunt) when just covering ground.
One thing I do like about the barrel being near your face is that it makes a pretty hand support for using your bino's 'offhand'.
