Secondly, the line-of-sight check to see if a hook should connect or not is now checked from Roadhog's position, instead of the hook's position. This basically means the hook can't connect to targets that Roadhog himself can't see.
Lastly, there is a new persistent line-of-sight check back to Roadhog once the hook has landed. If this check fails, the hook breaks off and returns to Roadhog. This means if you get hooked and move out of LOS quickly (either you dashed, were falling, were pushed, etc), the hook will now break early and not pull the target.
I think theyll get Roadhog right if these two things work as they say it should work. Being hooked when you were already around the corner and completely out of Roadhogs LOS is completely frustrating.