Feral is good but it is also HEAVILY gear dependent, and is from many peoples experience one of the most difficult DPS melee specs in game.
It takes some learning to get good at and require more than just being good at your spell rotation, but once you get that “eureka” moment and realize how Feral works you feel VERY powerful playing this spec.
But like I said it is VERY gear dependent.
And if you were like me as I were at the start of BFA, where I didn’t care that much about traits and just picked what seemed best, you WILL fail as Feral. Feral is literally broken without the right gear, and this is where people get frustrated and starts ranting about “Feral being a bad spec”.
So all in all Feral IS good, but it suffers from “bad exposure” from players who thought they could just pick it up and play it by JUST learning the proper spell rotation.
If you aren’t the type of player that likes grinding for specific gear, but want to do high end mythic+ runs, Feral isn’t for you. You NEED to be willing to get the right gear.
Without the Masterful Instinct trait you will die very easily in PvP. But if you have at least 2 of this trait on your gear you will feel very tanky. With 3 of it you will become more tanky than a Pally.
You will also need Jungle Fury as a trait, and preferably 2 of them. It will help with Ferals “critical strike” which is crucial for high dmg as Feral.
For mythic+ your azerite trait setup will be different, and I can see others have mentioned it above so I won’t repeat it 
With these traits you essentially just need to pop Survival Instincts, which is your main defensive spell, at the start of a fight and you will stay alive for much longer. And then make sure you use Tigers Fury at the right time during your rotation
AND of cause learn the proper rotation hehe
Oh and just to mention it. If you plan on doing higher mythic+ dungeons, you probably won’t get picked first. The reason Feral isn’t recommended for dungeons is not that our dmg is bad, it is because we lack utility. People will always ask you to “go Boomie” if you play with “hardcore” mythic+ers 