Thankfully, I wrote this out on another thread.
The characters were generally some of the worst BioWare has written in recent games.
What matters is not diversity or backgrounds. What matters is conflicts and the resolutions to them. Conflicts are what make great characters, and that regard, Inquisition is pretty vapid.
How many times do any characters in Inquisition face genuine difficulty? How many moments do any of the main characters, including the Inquisitor himself, face fear or despair or desperation? Very few. And if you're looking at conflicts with strong resolutions, it's even fewer.
I mean, let's review the conflicts characters face.
Inquisitor - Only real struggle is at the attack on Haven, and even then, there isn't a lot of fear shown. For the rest of the game, pretty much nothing.
Sera - Nothing.
Vivienne - Nothing.
Varric - Nothing. Gets very, very, very mildly upset with Bianca. Whatever the reason was is so forgettable that I can't remember it.
Dorian - Very weak. If he was in actual danger, it could have been stronger. As it is, his father is polite and nonthreatening and really does just want to talk to him. It's more bringing up unpleasant memories than anything else, which isn't very strong of a conflict at all.
Bull - I get what they were trying to do, but just fell flat for a half dozen or so different reasons.
Cole - Not terrible. He does get angry, but it's resolved rather quickly and simply. Works okay as a peripheral character.
Blackwall - Started out very promising, and then just fizzles out. He's pardoned, things go back to normal, nothing really meaningful gets said.
Solas - Not bad. His own mission was simple, but he has some compelling dialogue in the Arbor Wilds and such. If he was made mandatory, he could have had stronger interactions with Morrigan and the ancient elves.
Cassandra - Weak. We've been thoroughly exposed to how corrupt the Templars and Seekers and Chantry are by the time we get around to it. Her romance and desire to be feminine does make up for it somewhat, although that's obviously not something all players will see.
Cullen - Eh. He's firm in giving up Lyrium and a tough guy. There's never any real doubt that he's going to be fine.
Josephine - Again, we know full well she's going to be fine.
Leliana - Lame. And I just wanted to smack her for being stupid.
Morrigan - Pretty satisfying, although somewhat diluted by nobody knowing what Flemeth is up to and her motivation to drink from the well not being quite as strong as I'd like. Still, when she drops to her knees in despair when she thinks she's going to lose her son, it's as powerful a moment as any other I can think of in Inquisition. There should have been many more moments like those.