I love the flagline harness. I have one for each of my dogs: Labrador and Cocker Spaniel.
The harness is easily adjusted and both dogs seem to find it comfortable.
I am easily able to lift my spaniel over or out of situations - it is this safety aspect that I find so useful.
With my Labrador, I am able to guide him away from 'things' he may be tempted to eat while out on a walk.
I also easily recognise both dogs when they are off lead, which is an added bonus on a crowded beach or park when you have a common breed. Would recommend.