OK, so having played the game for a week, I have some balancing suggestions for Blizzard.

• The game really needs some anti-cheat system if it doesn't have one. In addition to the video everyone's seen of the Widowmaker whose sight kept snapping back to an invulnerable person's head, I saw a McCree who was getting headshots for every normal shot regardless of distance.
• Soldier: 76's Biotic Field needs to be destructible. Right now, a team of 5 Soldier: 76s and a Lucio can withstand everything short of an ult because they can simply keep using these in waves.
• JunkRat's Trap should be visible to the other team, even if it's less obvious to the other team than to your own.
• The defense spawn room for Temple of Anubis needs to be moved back. It's far too close to the point and gives the defending team an advantage it shouldn't have. You could argue that the Volskaya Industries spawn room also needs some tweaking, but it's not quite as bad.
• The mech pistols for D'va are a bit on the weak side. Her pistol when she's outside of the mech does considerably more damage, which is just... weird.
• Tracer needs to be rethought. Most heroes have weak to medium normal abilities and a crazy good ult. Tracer has crazy good normal abilities and a (relatively) weak ult. Maybe some cooldown adjustments?
• Genji's normal attack deals way too much damage. Maybe balance that a bit?
• Junkrat's... well, see what I said for Genji above.
• Bastion's transformed form needs a nerf, most likely to its ammo count before reloading.