Overwatch's newest hero Orisa will be added to the main game next Tuesday on March 21st, one week from today. Blizzard's announcement comes almost two weeks after Orisa was officially unveiled and put in the PTR.
This doesn't necessarily mean that the Overwatch team is done tweaking Orisa, as they have already decreased her magazine size and increased her ultimate cost, but it means that, ready or not, she will be live in one week from today. If this worries you, I suggest doing your placement matches before that date.
Here's everything you need to know about Orisa
Lore
She's Created By An 11-Year-Old Super Genius
11-Year-Old super genius Efi Oladele was tasked with creating Orisa in response to an apparent Doomfist attack on the Numbani Airport that specifically targeted the previous model of defense bot, the OR15.
She Might Turn Out To Be Evil
I'm officially the conspiracy theorist on this one, but I've seen enough sci-fi movies to know that handing over your security to the whims of an all-powerful A.I. is seldom a good idea. At the GDC, Overwatch lead writer said that Orisa is a cross between Robocop and GlaDOS, so that should be everything you need to know
Abilities and Role
Shield Et. Al.
Orisa most-defining characteristic is her shield, a stationary, 900-health barrier that she can place at range, but she can also pack a punch with her other abilities. She can make herself immune to tall forms of crowd control, fire off a mini Graviton Surge and buff her teammates damage (a'la Mercy) within line of site with her ultimate.
Anchor Tank
The Overwatch team designed Orisa to be what they call an "anchor tank," which is to say that you can construct a team around her the same way people now build their team around Reinhardt. As I have already expressed, as have many others, there doesn't yet appear to be a reason to pick Orisa over Reinhardt. Reinhardt's shield has more health and can be moved after placement. We'll know for sure once Orisa goes live, but I'm unconvinced that she is a viable Reinhardt alternative, as Blizzard intends her to be.