Oh nice, the Season 2 PTR is already available. Reading over the patch changelog, here's the hero related notes:
The reduction in hitbox size of projectile weapons was reversed, woot!
Ult meter drains over the course of .25 seconds instead of 1 second when first triggered. Previously it was pretty generous for letting people keep their ults if they got shutdown trying to use it.
McCree's ult now works like everyone else's as far as meter is concerned. No 50% refund if he doesn't shoot or dies.
D.Va's block takes slightly longer before starting to recharge (1 sec instead of 0.5)
Hanzo moves 10% faster than before with an arrow nocked, and his arrows are 30% faster.
Mei's ult projectile goes through barriers and the radius is now 10 meters (from 8), exactly like they said they would.
Mercy's heal rate has been buffed 20%, and resurrected heroes end their recovery animation and are able to move and attack sooner (2.25 seconds instead of 3)
For Genji:
Double jump doesn't reset on wall climbs, dashing doesn't damage Widowmaker and Junkrat's traps and no longer skips over Junkrat's trap (he'll get grabbed by it mid-dash now). His dash can't cancel animations on his other attacks, a technique "pro genjis" used to do way more damage than intended. Finally, his ult is 6 seconds long instead of 8. I like these changes, they're more peripheral nerfs to make him more challenging than direct debuffs on his damage or skills.
Lucio's speed boost is now only +70%, instead of +100%.
Roadhog's hooks now more easily break when the the grab's invalid (through walls, around corners, etc) and returns the hooked player to where they were standing instead of sliding them around walls and shit.
Finally, Zenyatta's Orb of Discord was indeed nerfed in damage bonus from 50% tp 30%... but in exchange his regular m1 attack has been buffed from 40 to 46 damage. I'll take it!
Also for like the fifth patch in a row they have a note in bugfixes about preventing Reaper's shadowstep from letting him go out of bounds, lol