I trained my two Boston Terriers to walk using these harnesses. They work great to direct the dogs where you want them to be. They are easy to put on and take off. I highly recommend them for any dog that pulls. We tried one on my son's dog Bailey who pulled a lot and it made such a huge difference. With the harness she is easy to walk now. With a collar and leash it was a very frustrating and unpleasant experience because she pulled so much.
The only problem we have with them is the leash gets underfoot with my female Phoebe who is a wild walker and tries to pull if given the chance. I think this harness is a much more humane way of walking a dog who pulls, rather than pulling on their neck you can control them from the shoulders and chest.

Pros: discourages pulling, leads from front so dogs don't get choked or pull like a sled dog

Cons: leash often gets under foot

this stops the dogs who pull very much. it doesn't take too long either. before you know it, they're walking at a good stride. the walk is so much more enjoyable and it is good training for the dogs to get out of the habit of pulling so much

Pros: stops the pulling

Cons: n/a

great for taining dogs to walk with you and not ahead of you

Pros: great for training

Cons: nothing