I have no personal experience with this halter, but I have two neighbors who are both using these on their dogs. One has a JRT mix, and the other has a larger Lab mix.
The JRT has figured out a way to pull his legs out of the harness, so the neighbor has stopped using it and went to a Martingale collar instead. The neighbor with the Lab was having issues with it rubbing on her dog's "armpits" and went to an Easy Walk harness.
Like I said, this is not my personal experience, but maybe it helps.