I'll also give my opinion on new characters from MKX (not counting this piece of crap named Triborg and Tremor which is technically not new at all)
Great:
D'Vorah - design-wise: original as hell and really fitting MK world. Plot-wise: responsible for the biggest twist in the story and most memorable killings. Overall: badass, grose and great. We need more of her!
Kotal Kahn - great design, cool backstory showed in the comics. He spreads the feeling that he is someone more than just and antagonist, and can become more like an anti-hero moving forward.
Erron Black - cool design, even if he is ONLY human, he is not bland and he covers cool archtype. Should have been more explored in the story, but maybe this time it will work better. If NRS really want to create more human characters, that's the path they should follow.
OK:
Cassie - I can't say I dislike her, eventhough I still don't get how she can beat Shinnok in his supersayian form. It's just too many Cages in one game. But she was well received, so I don't mind having her in MK11.
Takeda - when I saw the comics, I though that he would be main protagonist. Turned out other way, but still he has a good potential to be explored, cool backstory and I have hope that he will look less like generic SF character and more like ninja
Ferra/Torr - great idea, but potential a bit wasted. First of all, I can't remember any significance in the story. Secondly, personality was kinda weird. Maybe we should have seen more of their breed to get into they're story more. Well, maybe in future games, but I'm afraid that NRS gave up on them which would hurt me.
Bad:
Kung Jin - terrible name, terrible personality and mostly remembered by me from defeating Kotal. The thing that should not happen like EVER in MK Universe.
Jacqui - biggest NRS mistake IMO. Bland, boring without anything that can really save her. Let's not pay attention to the online stats, because they say shit. She was super annoying with her full-auto, therefore she was widely played - that's the whole story. Hoped not having her (and her dad) in next game, but seems that I need to live with that.