I can see how this tool would be very handy, and definitely better than just placing them by hand. I've done that, and its hard the on the fingers that are trying to place the brick as close as possible to the next bring, and you end up hinging it into place which also upsets the sand layer. And hard on the knees and back as you crawl along placing bricks, and constantly bending over and standing up.

Being able to place the brick straight down would be very nice! So to me this tool has a lot of advantages over the purely manual method. While it could probably use some refinement or adjustment on handle placement, it's on the right track for being much better.