During Blizzcon 2017 the Overwatch team announced the long-awaited 26th hero - a highly aggressive support hero by the name of Moira. Much like Sombra which was also announced during Blizzcon, Moira made her way onto the PTR a mere couple of days later, a place where she would only stay for about a week before finally being unleashed upon the live servers.
However, while Moira has been available in Quick Play and Arcade game modes for around a week now, she has not been unlocked in Competitive Play in order to give everyone a chance to try her out, as well as hopefully devise some counters. And now, as you can probably guess from the title, the floodgates have finally been opened and Moira is available in Competitive Play as well! Whether you consider this to be a good or bad thing, that will probably depend on your willingness to play her, but either way I would recommend waiting at least a day or two for people to stop instantly picking her without even knowing what her abilities do.
As for whether she's any good or not, I would say the answer is a definitive yes. I'm not sure if she can solo heal your average flanker-heavy team composition, but I did find her to be quite effective when combined with a secondary support like Lucio or Zenyatta. They not only add to her innately aggressive playstyle, but they're also excellent at topping off those pesky Genjis and Tracers that are a bit of a nightmare to hear with Moira, so the combo is definitely a powerful one.
When it comes to specific tips, there are a few things I would like every Moira to know:
• You are a healer, so don't watch your entire team die around you while you fruitlessly try to tickle a Roadhog to death.
• Your ultimate does a lot more healing than it does damage, so focus on keeping your team alive rather than trying to only blast your enemies apart. This goes doubly so if your team is stuck in a Graviton Surge or under attack by a Dragonblading Genji.
• You can jump at the end of your Fade ability in order to preserve momentum and propel yourself even further forward. It might not sound like much, but it makes you ridiculously hard to catch.
• When in danger, don't throw your orbs directly at the ground as they're just going to fly into orbit and be useless. Instead, throw the healing orb in the direction you want to run away so it can constantly top you off while you hopefully buy enough time to Fade to safety.
• Don't waste all of your resources healing squishy (200hp) characters. Simply spraying them with a bit of healing and then leaving the heal-over-time effect to top them off is often enough. This is going to be a bit of an acquired skill, but its one that you will need to learn if you want to be an effective Moira.
That's pretty much it as far as my insights are concerned. Everything else you'll have to figure out through a lot of practice, or by observing the cool tricks other Moiras do in your matches. And as a final note, here's a brief overview of her abilities, just so you know what you're going up against. Have fun!