Well I'm back from the theatre and here are my spoiler free thoughts.
First, I liked the movie, but I understand why it gets mixed reviews and even straight bad reviews from some critics. I think you need to be somewhat knowledgeable in the DC lore and a comicbook enthusiast if not a fan to truly understand and like the movie, otherwise quite a few things will go over your head or even seem plain weird. With that said, it is weird sometimes, especially with the dream sequences. There are more than one, I found them rather good, but they do break the pace and even the tone IMO. Confirming what I've read, I agree that these two are a bit all over the place. Was a bit unsettling but in the end it didn't bother me that much.
Now, Affleck was indeed both an awesome Bruce and a ruthless Batman, he might be the best live action batman ever.
Cavill surprised me, I thought he showed a bit more emotion and his superman is definitely heading more towards the Boy Scout every one here seems to want to see.
Gadot was very good too, although her role is not that big, but she definitely kicks ass.
Eisenburg was fine, albeit a bit over the top. He's not the serious imposing Lex the JLA cartoon or most of the comics, but this Lex is actually Luthor Jr. His father must have been that Lex we know, while he's a lot more sleazy, cunning and borderline deranged actually.
The movie did address the critics MOS got, meaning both fights took places away from civilians if that was a bone of yours, and I found them surprisingly short, even a bit too much for my taste, I wanted more ! About the last fight though, it's not a spoiler that the trinity fights Doomsday, but they really worked together and that was pretty awesome to see.
All in all I had fun, and it definitely did make me want to see the rest of the DCEU ASAP. But like I said, I see the flaws and I don't think it will reach the billion at the BO, it's just not accessible enough for everyone.
This review is very appreciated. :thumbsup