Well, not exactly "see". I know someone who was (is) heavily involved in the dubbing process of the movie in my country. Unfortunately, signing an NDA is not enough, the copy of the film they receive comes with most of the image covered, a big watermark with the name of the company responsible for the dubbing and they can only actually see the mouths of the actors so they can sync the sound with the lip movements. Which means this person didn't actually "see" the movie, more like a better version of a script reading.
So what I was told is that it's great. Keep in mind this person is not a big super-hero fan, but he-or-she said the story is very interesting and surprising. Batman is really, REALLY dark as you already know, with scenes that could've come from a horror film (although his interactions with Alfred are fun and this Alfred is particularly emotional. I'm not sure what it means, but that's what the guy-or-girl said). Superman was what he/she thought was really interesting, though. It was the first time Superman felt like a truly complex character (this person saw Man of Steel and thought it was ok but said he/she can barely remember the film) and his confrontation with Batman is only topped by his interactions with Lois, which I was surprised to hear.
Another cool part of the movie was Lex Luthor, which the person described as "equally funny and scary, but in the end you kinda feel sorry for him" (I'm paraphrasing here, by the way).
Now I finally asked him/her about Wonder Woman, and he/she said she was very interesting and Gal sounded sexy (?) in the role, but apparently her big standout scene is the final fight with Doomsday and the person couldn't actually SEE it for the reasons I said before, so that's a bummer.
Now to be clear here, this was a relatively fast conversation with someone I know but we're not very close, so I was trying to not look like an annoying nerd, especially considering this person signed an NDA, which I tried to respect. It's not too detailed but it's a reaction and I totally believe it's legit. The person looked really excited about the movie, so that's good news.