So, I'd like to make it clear already at the start: it's fine if you or kids like the show, I just can't personally get into it. To avoid of the anger of the fans - this is NOT the absolutely worst of the trash, but it's not a precious gem either.
Also, keep in mind, that this is ONLY MY PERSONAL OPINION & I'm glad you liked it.
The animation is OK. It's not very ugly, but I wouldn't call it especially artistic either. The style kinda reminds me of "Peppa Pig", with a prettier coat of paint and nicer character designs. All in all, the animation isn't outright bad, however it doesn't mean I haven't seen better.
The effects totally work, to the show's credit.
I can't put my finger on the voice acting. It's pretty good. It might not be on "Avatar: The Last Airbender" level, but it's not ear-grating at least. Hey, they talk like normal people!
The dailoge isn't painfully bad or gibberish.
My biggest problem with the show is how abstract and non-sense the it is. Now, "RedaKai" or "MonSuno" weren't super normal, but they were imaginative , entertaining and clever (I know they have foul reputation, but still, I love them). But back to "Nina needs to go!", it's also boring to me, inspite of being fast-paced & motion-packed. Well, the creators were at least trying, but this isn't it yet. Not for too long.
So, in conclusion, "Nina needs to go!" is not a great show, but not garbage either. 3\10 for now.