Although our Westie is a little on the small side (18 pounds) he's pretty stubborn and pulls and pushes with a regular leash as hard as he can. The PetSafe gentle leader put a stop to that right away, and now we can walk him with piece of mind that he isn't injuring himself on his old collar.
It took about a week for him to adjust, but once he got the hang of it he doesn't seem to mind it. In fact, he gets excited when we pull out the gentle leader, because it means we are going for a walk.
One complaint I have with this item is that the plastic buckle that holds the nose loop is a little flimsy and made of plastic. Although nothing has happened to it yet, it seems to be a weak point on the entire construction of the leash.