Alright, so Moira's
pretty damn good. Like with Sombra and Doomfist releases, she's another hero that's absolutely worthless if you use her incorrectly - only this time, she's downright amazing if you don't, and solving that problem for the enemy team isn't as simple as picking up a good Winston or a semi-competent McCree or Soldier.
It's entirely possible that some things about her, like the cooldown on her invulnerability dash or the lock range on her damage orbs, are gonna get some hella nerf. It's also quite possible that other things, like her literal inability to deal any damage to Torb turrets, will get fixed/buffed. In the meantime, here's some things to keep in mind if you're trying it:
Moira's literal inability to deal damage to Torb turrets: This is a rock fact. The only possible way Moira can damage a Torb turret, as it stands right now, is to melee attack it. Well, that or ult it. Right-click and damage orb do nothing, although oddly enough, right-click works just fine for killing Symmetra turrets. (Orb still doesn't, though, which is fair 'cause it'd be broken at it otherwise.)
Moira's healing: Is like an AoE Mercy heal in front of you, and that's not even counting the orbs. Just be sure to farm up biotic charge with the right-click, because if you're focusing on healing all the time then you're gonna run out of that charge before you know it, and it refills
really slowly on its own.
Moira's right-click mode: Is much longer-range than you think. It doesn't lock on like Symm beam does, though, and it doesn't give the audio tick to let you know when you're dealing damage with it (nor does it visibly do a whole lot of said damage), so it can be hard to tell at first just how far away you can hit people from. The answer is: Surprisingly far, but you have to actually aim it right at them.
Moira's dash: Sweet, sweet fuck, but this is a powerful ability. Hella fast, guided dash which makes you invisible and, perhaps most importantly,
makes you completely invulnerable. Junkrat ult ain't shit. D.Va ult ain't shit. Look death in the eye, hop, step, and laugh. And on a six-second cooldown, too - what the heck, Blizz? I mean, I'll take it, but...
(Also: As it stands right now, Junkrat trap does not prevent Moira from using this ability. It does, however, still prevent her from moving while cloaked and invincible. Further testing required to determine if Gravitron fails to block it as well.)
Moira's orbs: If you're dueling somebody or trying to back up a team that's fighting in front of you, healing orb is likely the way to go. Unless the person you're dueling is best fought by bursting them down hella quick, or your team doesn't need a Zenyatta-ult level of healing for the fight, in which case damage orb is totally the way to go. Either way, be sure to keep in mind the bouncing. Moira's a total boss at fighting in tight spaces because of it, and bouncing it around corners at long range is a great way to farm ult charge.
Here's a pretty good example of the latter.
Moira's ult: Not nearly as powerful as the preview video would have you believe, but still a decently good ultimate thanks to its general utility and low charge requirement. Like with her orbs, good zone control is the key to using this ult; you want to run it through as many enemies and as many teammates as you can get lined up together in front of you, so you can damage a bunch of enemies while healing a bunch of teammates, and said teammates can take hits for you in the meantime because you're extra fast, but still vulnerable while you're using it.
Here's a pretty good example of a nice ult lineup.
In closing: Hella fun character to play. Slightly tricky, but not too hard to get the hang of after a little bit. Capable of doing hella damage, hella healing - and without even needing to sacrifice the one for the other. Whether she needs serious nerf or not remains to be seen, but I wouldn't be too surprised to see it happen pretty soon.