This is an excellent invention given how frequently restaurants (and other people's houses) don't have highchairs.
It straps securely, has a padded bottom and is easy to clean. It also packs flat so is easy to transport. The material and stitching are first rate and we have had no problems with the item wearing or falling apart (which I thought might happen).
The only downside is that because the sides are made of material they can collapse a bit if the child bends down to one side, but this is only to be expected with such an item (unless you want to buy a rigid chair, but this would be a pain to take everywhere).