TLDR; It's extremely good but there's a few flaws.
Girl from Nowhere is an extremely stunning show, the production quality is through the roof and the practical effects that are used in the episodes to depict gore are phenomenal. The soundtrack is super catchy and I find myself humming the main theme every now and then. The acting in the show is also top notch. I've never seen a Thai TV show before and I hope all others are of the same quality of this, though I might be disappointed. (Note, I didn't watch the dub, I watched with subtitles and original audio.)
The themes that are used in each episode of the show are very real, they deal with morality and the psyche of people. There are very triggering though. There's suicide, sexual assault/abuse, death, bullying, crime, and violence. That's just to name a few, however. This show isn't for the faint of heart whatsoever so please be consider what triggers you and what doesn't, this show doesn't hold back.
The lack of a plot in season 1 I find myself liking a lot, surprisingly. It makes you think "What will Nanno do next time?" after you've watched an episode. Each time she does something rather evil, I can't help but smile wickedly with her but that might be just me.
Season 2 I don't like as much but can I see why Yuri is needed. For other people, the show might get bland quick because every episode is just Nanno going to a new school, ruining one or more lives, then moving on to the next. I don't mind the repetition however, every single episode is entertaining in my opinion.
Chicha Amatayakul was an absolutely amazing casting for Nanno's character. She captures her insanity and manipulation perfectly. The crocodile tears she gives are very believable and her laugh ... Oh my gosh her laugh.... Her laugh is so chilling, it isn't just a simple stereotypical villain laugh. It's much, much more. It's absolutely deranged and shows how much fun she really has with messing with people. The personality she has is superb, she really does act like a malignant force corrupting everyone and everything and it feels super smooth.
All in all, I do recommend the show if you're looking for a good psychological horror that isn't afraid to get dark fast.