I am 115 lbs. and 5 ft. 2 inches tall, ( and hope to take off 10 lbs. more)...Dale is 100 lbs ( and probably is still going to put on 10 more lbs.) While Dale walks well on a leash, and isn't generally a puller...i could NEVER walk him securely w/o using the pronge. I am so happy to have it. If we are walking down the street, and he sees another dog, he does, naturally, try to go towards it, and w/o the pronge on, I would be dragging behind him...since i only outweigh him by 15 lbs. The obedience trainer along with the owners, decided a couple weeks into obedience school which dogs needed the pronge, and Dale, being a giant breed, and a breed capable of pulling thousands of pounds, was certainly a good canidate for the collar. I recommend it to any large breed dog owner. He understands when it is on, that we mean business, and he is to walk well with us...he seems to forget, at times, that we are alpha. We certainly don't use it in any kind of negative way...just by means of controlling him around strangers and dogs while walking him...and people should know that it is a pinch collar, not a stabbing collar...when he pulls, it pinches him, to remind him to walk nicely. We also train him with treats, and positive reinforcement, but this is certainly a neccessity for us...and probably for a lot of large breed dogs.

I wanted to add: Before putting the collar on him, he is put into a sit, and does not try to get away when he sees the collar...again, it only pinches him, when he starts to pull...during the majority of the walk, he doesnt even feel it...it has slack to it...Dale is stubborn and if he doesnt want to go somewhere, either, he will stop like a mule, and is nearly impossible to move..so it assists us that way as well.
To answer the question more briefly, i do not think it is cruel at all.