Yes, people have different views about this.
It feels weird to me tho that giving the pain of stunning to slaughter is justified to reduce the pain of slaughtering, which also does not go away completely even when stunned. The animal is in full senses to feel the stunning. Pain must be there. Either don't do it or go with the shortest rout, and stunning is not it, I guess. Also, stunning prevents blood from properly leaving the body which could spoil the meat faster, make it of less quality to eat or stay valid longer and/or keep disease causing agents in the animal.
Halal slaughter is not only about slaughter anyway, it goes within a wider plan. The animal should never be treated badly, mutilated, or slaughtered in front of other animals. It also teaches to give the animal water to drink and pet it to calm it down. I know that still does not cancel the pain of slaughtering, but it absolutely better for the animal. Some views also say it is forbidden to slaughter/kill animals if there is no intention to eat them. I think halal negative critics (vs other slaughtering methods) only looked at the cutting part and ignored other parts like castrating males in farms, treating the animal like toys, torturing them while they are still in their full senses (stunning included), etc., which I saw on the videos and they are absolutely forbidden in halal slaughtering and teachings around it.
I don't disagree that it is cruel, by the way. I understand how no meat eating advocates feel. I tried to live without eating animals, but it made my life miserable and me always hungry. I can't live right without it.