Coming soon! In fact we plan to have it up on the PTR asap (might be this week).
For a bit of tldr; for what the changes are:
Firstly, the hook victim will now move in to the position directly in front of Roadhog, rather than just a straight line towards him. There is a cap on how far 'to the side' you can be pulled, so you can't just hook someone, spin 180, and dump someone off a cliff. This part (along with some other bug fixes) should generally make the hook feel more consistent as to where the victims get pulled.
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.
Overall these changes will likely make Roadhog a bit weaker, but we'll evaluate his performance once we get people playing him and make adjustments as necessary.