Forgetting for a second all the lore that goes into Orisa, Overwatch's new, potentially very evil hero, she is, first and foremost, a playable character in a competitive video game. Orisa is the sixth Tank hero and was designed specifically, as the developer update above states, to provide players with a viable alternative to Reinhardt to shake up both the casual and the competitive/tournament metagame.
It's an admirable goal. I have gone on the record stating my dislike for how ubiquitous Reinhardt is and the Overwatch meta that requires either a Reinhardt-led deathball or a strategy specifically designed to counter a Reinhardt-led deathball, so it's nice to see the Overwatch team really taking a look at how it emphasizes barriers and what they can do to create alternate styles of play.
But, is Orisa truly the tank that can substitute for a good Reinhardt and provide alternate styles of play? In her current state, I have my doubts. She very well could be, but it would require some tweaking of not just her, but perhaps the big man with the big hammer as well.
Shield Comparison
Orisa's shield ability can be fired out in front of her, and it creates a stationary barrier. This barrier has both a timer (a generous one, though) and a static health pool of 900.
Reinhardt's shield is mobile, as it's attached to him and moves as he moves, and it has a health pool of 2000 that recharges while Reinhardt has his shield deactivated.
Advantages And Disadvantages
Reinhardt has the advantage of being able to move his shield. This means that an offensive Reinhardt is completely viable, as he can move his team forward behind him. His shield also has 1100 more health than Orisa's, which obviously means its a much more formidable option.
Orisa's shield perhaps has more tactical uses, though. Since it can be deployed from a distance, she can use it to protect teammates whom she is behind. So, approaching a group of teammates being fired upon, Orisa can shoot her shield out in front of them, even if she herself is not in front of them.
Orisa also has the advantage of not being essentially disabled while her shield is active, so she can shoot, and use her other skills, and have her shield up at the same time.
Potential changes
Still, though, it's hard for me to see Orisa as a Reinhardt alternative when her shield is immobile and has less than half the health of a Rein shield. People use Reinhardt as a way to push into locations rather than simply sitting back.
And, if you are on defense, you could conceivably have Orisa rather than Reinhardt, and simply plop her shield down at a choke point, but a Reinhardt shield still has more health, so it might not be worth it. It could be balanced out by Orisa's continued offensive capabilities while her shield is up, but the jury is still out (playtesting, I imagine).
I would think that you could simply buff the health of Orisa's shield, but it may be necessary, now that we have an accurate counterpoint, to nerf Reinhard's shield health. I would suggest a drastic nerf, actually, perhaps moving his shield down to 1000 health and moving Orisa's shield up to, say 1500 or maybe even closer to 2000.
This would really make players choose between the two. Do I want a stronger, immobile shield, or a weaker, mobile shield? That's a tradeoff that players would have to consider. As of now, even with Orisa's continued offensive capabilities, I'm not sure competitive or tournament players are going to think twice before picking Reinhardt.