Along with their newest hero Ana, Blizzard released a slew of meta-changing Patch Notes that will be released with the new character, and all of which can be tested on their new Public Test Region server. The PTR is open to all Overwatch players, regardless of their level or location. In order to participate, players must install the PTR through the Battle.net client. Players can do this by selecting "PTR: Overwatch" in the server list above the "Play" button. After a few hours you'll be able to access the server. Currently, the PTR is experiencing heavy traffic so it may take a few tries before you can get into - if you're determined, just wait it out. The PTR is available in all regions except China. Players outside of America may experience some additional latency or connection issues, however. Blizzard says the purpose of the PTR is mostly to detect bugs and technical problems, not necessarily for balance purposes, but players can still submit recommendations through the usual channels.
The PTR currently has already implemented the entire patch, including Ana, and a special Brawl featuring her. There have been some changes to Competitive Mode and in general. Competitive Mode will now only allow one of each hero per team. Blizzard expanded on this particular change, saying that hero stacking was being used in a way which ruined some of the fun of the game, and could often be difficult to counter on certain maps. Since the change was fairly easy, Blizzard was able to implement it this patch. All Overwatch games regardless of mode will also see changes in the Overtime structure. The new Overtime counter will now go down faster after a game has been in Overtime more than twenty seconds, and players will take 2 additional seconds to respawn while the game is in Overtime.
Greater meta changes have been made to healing and ultimate charging. Because self-healing abilities will now help players charge their ultimate, several heroes now have to charge for a bit longer to make up for it. These include Lucio, Roadhog, and Soldier: 76. Mercy saw some quality of life changes to her ultimate - in exchange for a longer charge time, she can now move while casting her ultimate, and her Guardian Angel will reset upon use of her ult, allowing her to swoop in and out of battles easily. Her Bonus Damage was also increased to 50%, though it will no longer stack with a second Mercy. McCree saw a bit of a buff in this update to counteract some of his debuff from last time as they are allowing Peacekeeper to do full damage at longer distances then before.
Zenyatta and D.Va saw the most changes overall. D.Va's Defense Matrix is now set to the players RMB, and will now have a 1-second cooldown. However, it will be based on a charge. The shield will last for 4 seconds, however, the player can cancel the shield at any point during those 4 seconds. Then it must recharge. A full recharge will take 10 seconds, decreased incrementally depending on how much was used. D.Va's ultimate also saw a buff with it no longer damaging herself, having its cost decreased by 15% and the delay on utilization cut down by one second to 3 seconds. Zenyatta received some major buffs to his Orbs, both receiving a heightened projectile speed. He now has a base health of 200 with additions to his shield, and the healing on his ultimate is increased. Additionally (and hilariously) his movement speed doubles upon using his ult as well.
One noted change is that they have added long requested 21:9 support to the game with the PTR. However, according to users on Neogaf, that 21:9 support is essentially just cutting part off the top of the screen.
With the addition of Ana, the current meta seems to be moving towards a healthier experience for Support heroes, and generally to how sustain works in the game. You can try all of these changes on the PTR before they hit the main servers.